Boiler madness

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Joann provetto

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i will try to make this short

Moved into new to us house 6 months ago. 36 yr old boiler condemned first day. New to area found unscrupulous unlicensed ( unknown at the time) plumber to replace gas fired baseboard heat. 4 zones. Basement radiant in kitchen rest of main floor and upstairs. It seems that the heat upstairs does not work unless heat in basement is on. Found a reputable master plumber to take a look. Recently replaced the zone valve ( although the it was replaced in March) thinking it was defective. Still no heat upstairs. Kept saying I think somehow it s related to the basement therm needing to be on. Said something about an "n" switch. So frustrating. Not only did the first guy do a terrible job, i paid double what I should have. And then he tried to put through another 2000 charge on my credit card. Awful man. So the plumber that replaced the zone valve said I need an electrician and still waiting for the guy he recommended to call. This was a problem as soon as boiler replaced six months ago. But since heating season was almost over and the heat did work, albeit in a weird way, we let it go til now.. Just want to understand how it works My other house as electric heat ( and not any more expensive than people who had gas oil) so this whole system is new to me. Thank you in advance. Weil McLean system
 

Jadnashua

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WRT the 'n' switch...he probably mean end switch, often part of the zone valve used to provide some control logic. Without a lot more information, what you've provided is not enough to diagnose your problem.

Are there more than one set of thermostats in the house? It sounds like the first floor zone is properly hooked up to the boiler to cause it to turn on, but the second floor's thermostat is only controlling the zone valve with no feedback to the boiler to tell it you need heat. If upstairs was cold enough to open the zone valve, there would be no heat until the first floor's control told the boiler, which would also turn on the circulator to push the hot water there. The zone valve's end switch could be used for that I think, but without knowing how your system is setup or wired, exactly how to make that happen, or even if it's the best way, I can't say.
 

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WRT the 'n' switch...he probably mean end switch, often part of the zone valve used to provide some control logic. Without a lot more information, what you've provided is not enough to diagnose your problem.

Are there more than one set of thermostats in the house? It sounds like the first floor zone is properly hooked up to the boiler to cause it to turn on, but the second floor's thermostat is only controlling the zone valve with no feedback to the boiler to tell it you need heat. If upstairs was cold enough to open the zone valve, there would be no heat until the first floor's control told the boiler, which would also turn on the circulator to push the hot water there. The zone valve's end switch could be used for that I think, but without knowing how your system is setup or wired, exactly how to make that happen, or even if it's the best way, I can't say.
Thank you. I think I understand. In case this helps, there is one therm in the basement. 2 on the main floor ( one for radiant in kitchen seems to work fine, independent of anything else) another one on the first floor that heats all other rooms ( living room, dining room, mud room, small bedroom and bathroom). 2nd floor One programmable therm in master bedroom that heats master , second bedroom and bathroom). House is 1800 sq ft cape. I have change batt and reprogrammed the master therm so it don't think that is it. The upstairs def does not get heat ( even when the room is cold and therm set really high) unless the basement therm is on. When I turn on basement therm I can see boiler and kicks in immediately and heat goes on on 2nd floor. If I turn it off and do the same with the maste br nothing happens. The boiler guy seemed stumped. Am I correct in thinking this is a wiring issue?
 

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It is likely a wiring issue, but it may take a zone controller to make it all work right. Sounds like you have five zones, and the 'stock' boiler may not support that many without additional hardware. FWIW, breaking a small house down into that many zones is asking the boiler to short cycle which is both inefficient and leads to increased wear and tear on things. It would be better to adjust the flow to balance things out and use fewer zones. You'd likely be more comfortable and save money. Ideally, the boiler would run constantly, just meeting the needs, but that would take a large variable output range, and most boilers can't support that. Some come close if sized properly, though.
 

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It is likely a wiring issue, but it may take a zone controller to make it all work right. Sounds like you have five zones, and the 'stock' boiler may not support that many without additional hardware. FWIW, breaking a small house down into that many zones is asking the boiler to short cycle which is both inefficient and leads to increased wear and tear on things. It would be better to adjust the flow to balance things out and use fewer zones. You'd likely be more comfortable and save money. Ideally, the boiler would run constantly, just meeting the needs, but that would take a large variable output range, and most boilers can't support that. Some come close if sized properly, though.
 

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I
It is likely a wiring issue, but it may take a zone controller to make it all work right. Sounds like you have five zones, and the 'stock' boiler may not support that many without additional hardware. FWIW, breaking a small house down into that many zones is asking the boiler to short cycle which is both inefficient and leads to increased wear and tear on things. It would be better to adjust the flow to balance things out and use fewer zones. You'd likely be more comfortable and save money. Ideally, the boiler would run constantly, just meeting the needs, but that would take a large variable output range, and most boilers can't support that. Some come close if sized properly, though.
i appreciate your help. Will post more when the electrician shows to sort it out
 

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I'm almost afraid to ask, but which model & size Weil McLain did the unlicensed hack install?

How many feet of baseboard is there, broken down by zone?

jadnashua has it right: In a 4 zone system with low mass radiation like baseboard, if it's ridiculously oversized for the radiation it's both an efficiency and longevity problem. There may be reasonable cost fixes to mitigate both of those factors, but the napkin-math review of the system design should be done, even if it's after the fact.
 

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I'm almost afraid to ask, but which model & size Weil McLain did the unlicensed hack install?

How many feet of baseboard is there, broken down by zone?

jadnashua has it right: In a 4 zone system with low mass radiation like baseboard, if it's ridiculously oversized for the radiation it's both an efficiency and longevity problem. There may be reasonable cost fixes to mitigate both of those factors, but the napkin-math review of the system design should be done, even if it's after the fact.

Hack? That's kind. Criminal is more like it. Thank you for responding

WM CGa Series 2. Gold. The manual looks like it is written for a couple of units so I cant figure out the size, But I recall "sizing up" and this one being around 90 (the smaller one was 60 ish) . The part number on the manual is 550-142-779/1112.

the feet of baseboards on

basement approx 64 ft

main level is approx 51 ft

2nd fl (area with issue) has 2 12 ft BB in master (odd shaped room about 19 x 18) L shaped. BR is 3 ft and other bedroom has 12 ft baseboard. Windows in house are decent Anderson casement 30 yrs old seems well insulated. Also, house is vinyl sided (which is very popular is this area however much I hate it, no offense) We are on eastern Long Island NY.

I assume the basement is a zone, kitchen radiant s a zone, main floor is a zone and second floor a zone. Although my inspector didn't break that down.
 

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You have to look at the name-plate specs on the boiler itself- the manuals typically cover the entire series.

The smallest of the series is the CGa-25, which has 44,000 BTU/hr of DOE output, the next is the CGA-3, which is physically the same size but with 59K of output. The CGA-4 is slightly wider, and has 88,000 BTU/hr of output, so I'll assume that's the one you have(?)

I'm going to assume the bedroom has 2 x 12'= 24' of baseboard, not 212'.

So total you have:

zone 1 - Kitchen: Radiant, of unknown type & tubing volume
zone 2- Basement: 64'
zone 3- Main Floor: 51'
zone 4- Master Bedroom: 24' Other Bedrooms: 12' + 3' , total 54' on the zone.

Total baseboard: 169

"Sizing up" from the previous boiler is almost always a mistake, as you'll soon see. Aside from the fact that existing boilers are typically 3x oversized for the actual space heating load, up-sizing the boiler without upsizing the zone radiation results in excessive cycling.

An early to mid 1980s 2 x 4 framed 2000' house with 1000' of basement with clear-glass (not low-E) double-pane windows will have a heat load at +15F (the 99% outside design temp for most of L.I.) of about 35-40,000 BTU/hr, maybe 50K if it leaks a ton of air and it's a walk-out basement. If it's 2x6 framing it'll be lower. A current code-minimum house that size & description would have a heat load ~35K. You probably would have done fine with the CGa-25, at half the output, which also would have cut the number of burn cycles by more than half.

Dumping 88,000 BTU/hr of boiler output into 169' of baseboard is 520 BTU/ft-hr, which will balance the baseboard output to boiler-input at an average water temp of 170F, which is fine, if it were all one zone, but it's not.

The max output temp is probably 220F, which optimistically speaking the most you'd have for average water temp is about 210F. At 210AWT the baseboard can only deliver 775-800 BTU/hr per foot of baseboard into the room.

When only your basement zone is calling for heat, 88,000 BTU/hr even into your biggest 64' zone is 1375 BTU/hr per foot , which is considerably more than the baseboards can deliver even at the boiler's maximum operating temp- it'll be cycling fairly often .

Then, 88,000 BTU/hr into the 51' main floor zone is 1725 BTU/ft-hr, which means during a continuous call for heat it'll be cycling on/off pretty rapidly at about a 50% duty cycle, even with the temps cranked to the max.

If you combined the main-floor and bedroom zones into a single zone, the room-to-room temperature balance may not track very well, but with a combined 105' of baseboard and 88,000 BTU/hr of boiler output you're looking at 838 BTU/ft-hr, which almost balances, and wouldn't short-cycle, (even though it'll still cycle some.)

It should still heat the house just fine once you get the zone controls & wiring sorted out, but odds are pretty strong that it's going to short cycle on zone calls if it's truly 4 or more zones. A short-cycling boiler will run a good 10-15% lower than it's rated AFUE, and will wear out it's ignition & gas-valving components more quickly.

Is the boiler heating your potable hot water too?

If not, one solution that would enhance overall efficiency & longevity would be to install a "reverse indirect" hot water heater/buffer tank and let all of the zones pull water from the buffer tank, and have the boiler only serve the buffer tank. You could play around a bit with the temperature settings on the buffer tank so that it delivers reasonable hot water performance AND keeps up with the space heating load. Assuming the real heat load is 40,000 BTU/hr (probably high, but maybe), with 169' of baseboard that's 40,000/169'= 236 BTU/hr per foot, which can be delivered at an average water temp of 130F. So if you set the tank temp to 140-150F it'll cover the space heating load just fine, but the boiler only fires when the average temp in the tank temp drops 7-10F below the set point (this can be increased if necessary). The thermal mass of the water in the tank and the temperature swing of the tank determines the minimum firing time, which is quite a bit longer than the cycling it would be doing with just a single smaller zone calling for heat.

Radiant.jpg



The potable hot water heats up instantly as it's drawn through the heat transfer coils in the buffer tank. At 88,000 BTU/hr you have more than enough burner output to support a 24/365 shower (providing you can stay awake that long! :) ), and at a tank temp of 150F you don't need a monster-sized buffer to fill a normal sized tub.

But before going down that road, get the controls figured out, and start timing the burns when say, just the kitchen zone is calling for heat, or some other zone. If it's under 5 minutes (probably is) it's slipping in efficiency. If it's under 3 minutes it's probably worth doing something about it.
 

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Wow. Thank you that s intense.

Master is 2 x 12

And boiler also heats HW. Dont remember size but it s average

If i understand this short cycling is going on and off too much which sounds like it will wear out the parts and not be efficient
That makes sense. It also sounds like there is too much output based on size of boiler and not enough baseboards so once baseboards reach their maximum output the boiler shuts off. Hence the short cycling. So if I combine two zones then there is more baseboard (ft) to accept the heat. I think I get it.

I definitely remember him saying better to go larger. The 88 btu sounds familiar but I will check the plate. I am sure it was to just charge me more.

Kitchen radiant added about 7 yrs ago to existing (aging) boiler by prior owner which didn't sound right to me. It heats up fast(tile floor) and stays warm. I actually don't think I like it. It s too warm for me and the dogs. Room really is toasty. My husband in the other hand loves it.
When you talk about balancing not sure I understand the calculation or what that means
I really appreciate your response who knew this was so technical. Any chance you are in the area and can fix it? Thanks again
 

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You have to look at the name-plate specs on the boiler itself- the manuals typically cover the entire series.

The smallest of the series is the CGa-25, which has 44,000 BTU/hr of DOE output, the next is the CGA-3, which is physically the same size but with 59K of output. The CGA-4 is slightly wider, and has 88,000 BTU/hr of output, so I'll assume that's the one you have(?)

I'm going to assume the bedroom has 2 x 12'= 24' of baseboard, not 212'.

So total you have:

zone 1 - Kitchen: Radiant, of unknown type & tubing volume
zone 2- Basement: 64'
zone 3- Main Floor: 51'
zone 4- Master Bedroom: 24' Other Bedrooms: 12' + 3' , total 54' on the zone.

Total baseboard: 169

"Sizing up" from the previous boiler is almost always a mistake, as you'll soon see. Aside from the fact that existing boilers are typically 3x oversized for the actual space heating load, up-sizing the boiler without upsizing the zone radiation results in excessive cycling.

An early to mid 1980s 2 x 4 framed 2000' house with 1000' of basement with clear-glass (not low-E) double-pane windows will have a heat load at +15F (the 99% outside design temp for most of L.I.) of about 35-40,000 BTU/hr, maybe 50K if it leaks a ton of air and it's a walk-out basement. If it's 2x6 framing it'll be lower. A current code-minimum house that size & description would have a heat load ~35K. You probably would have done fine with the CGa-25, at half the output, which also would have cut the number of burn cycles by more than half.

Dumping 88,000 BTU/hr of boiler output into 169' of baseboard is 520 BTU/ft-hr, which will balance the baseboard output to boiler-input at an average water temp of 170F, which is fine, if it were all one zone, but it's not.

The max output temp is probably 220F, which optimistically speaking the most you'd have for average water temp is about 210F. At 210AWT the baseboard can only deliver 775-800 BTU/hr per foot of baseboard into the room.

When only your basement zone is calling for heat, 88,000 BTU/hr even into your biggest 64' zone is 1375 BTU/hr per foot , which is considerably more than the baseboards can deliver even at the boiler's maximum operating temp- it'll be cycling fairly often .

Then, 88,000 BTU/hr into the 51' main floor zone is 1725 BTU/ft-hr, which means during a continuous call for heat it'll be cycling on/off pretty rapidly at about a 50% duty cycle, even with the temps cranked to the max.

If you combined the main-floor and bedroom zones into a single zone, the room-to-room temperature balance may not track very well, but with a combined 105' of baseboard and 88,000 BTU/hr of boiler output you're looking at 838 BTU/ft-hr, which almost balances, and wouldn't short-cycle, (even though it'll still cycle some.)

It should still heat the house just fine once you get the zone controls & wiring sorted out, but odds are pretty strong that it's going to short cycle on zone calls if it's truly 4 or more zones. A short-cycling boiler will run a good 10-15% lower than it's rated AFUE, and will wear out it's ignition & gas-valving components more quickly.

Is the boiler heating your potable hot water too?

If not, one solution that would enhance overall efficiency & longevity would be to install a "reverse indirect" hot water heater/buffer tank and let all of the zones pull water from the buffer tank, and have the boiler only serve the buffer tank. You could play around a bit with the temperature settings on the buffer tank so that it delivers reasonable hot water performance AND keeps up with the space heating load. Assuming the real heat load is 40,000 BTU/hr (probably high, but maybe), with 169' of baseboard that's 40,000/169'= 236 BTU/hr per foot, which can be delivered at an average water temp of 130F. So if you set the tank temp to 140-150F it'll cover the space heating load just fine, but the boiler only fires when the average temp in the tank temp drops 7-10F below the set point (this can be increased if necessary). The thermal mass of the water in the tank and the temperature swing of the tank determines the minimum firing time, which is quite a bit longer than the cycling it would be doing with just a single smaller zone calling for heat.

Radiant.jpg



The potable hot water heats up instantly as it's drawn through the heat transfer coils in the buffer tank. At 88,000 BTU/hr you have more than enough burner output to support a 24/365 shower (providing you can stay awake that long! :) ), and at a tank temp of 150F you don't need a monster-sized buffer to fill a normal sized tub.

But before going down that road, get the controls figured out, and start timing the burns when say, just the kitchen zone is calling for heat, or some other zone. If it's under 5 minutes (probably is) it's slipping in efficiency. If it's under 3 minutes it's probably worth doing something about it.
You have to look at the name-plate specs on the boiler itself- the manuals typically cover the entire series.

The smallest of the series is the CGa-25, which has 44,000 BTU/hr of DOE output, the next is the CGA-3, which is physically the same size but with 59K of output. The CGA-4 is slightly wider, and has 88,000 BTU/hr of output, so I'll assume that's the one you have(?)

I'm going to assume the bedroom has 2 x 12'= 24' of baseboard, not 212'.

So total you have:

zone 1 - Kitchen: Radiant, of unknown type & tubing volume
zone 2- Basement: 64'
zone 3- Main Floor: 51'
zone 4- Master Bedroom: 24' Other Bedrooms: 12' + 3' , total 54' on the zone.

Total baseboard: 169

"Sizing up" from the previous boiler is almost always a mistake, as you'll soon see. Aside from the fact that existing boilers are typically 3x oversized for the actual space heating load, up-sizing the boiler without upsizing the zone radiation results in excessive cycling.

An early to mid 1980s 2 x 4 framed 2000' house with 1000' of basement with clear-glass (not low-E) double-pane windows will have a heat load at +15F (the 99% outside design temp for most of L.I.) of about 35-40,000 BTU/hr, maybe 50K if it leaks a ton of air and it's a walk-out basement. If it's 2x6 framing it'll be lower. A current code-minimum house that size & description would have a heat load ~35K. You probably would have done fine with the CGa-25, at half the output, which also would have cut the number of burn cycles by more than half.

Dumping 88,000 BTU/hr of boiler output into 169' of baseboard is 520 BTU/ft-hr, which will balance the baseboard output to boiler-input at an average water temp of 170F, which is fine, if it were all one zone, but it's not.

The max output temp is probably 220F, which optimistically speaking the most you'd have for average water temp is about 210F. At 210AWT the baseboard can only deliver 775-800 BTU/hr per foot of baseboard into the room.

When only your basement zone is calling for heat, 88,000 BTU/hr even into your biggest 64' zone is 1375 BTU/hr per foot , which is considerably more than the baseboards can deliver even at the boiler's maximum operating temp- it'll be cycling fairly often .

Then, 88,000 BTU/hr into the 51' main floor zone is 1725 BTU/ft-hr, which means during a continuous call for heat it'll be cycling on/off pretty rapidly at about a 50% duty cycle, even with the temps cranked to the max.

If you combined the main-floor and bedroom zones into a single zone, the room-to-room temperature balance may not track very well, but with a combined 105' of baseboard and 88,000 BTU/hr of boiler output you're looking at 838 BTU/ft-hr, which almost balances, and wouldn't short-cycle, (even though it'll still cycle some.)

It should still heat the house just fine once you get the zone controls & wiring sorted out, but odds are pretty strong that it's going to short cycle on zone calls if it's truly 4 or more zones. A short-cycling boiler will run a good 10-15% lower than it's rated AFUE, and will wear out it's ignition & gas-valving components more quickly.

Is the boiler heating your potable hot water too?

If not, one solution that would enhance overall efficiency & longevity would be to install a "reverse indirect" hot water heater/buffer tank and let all of the zones pull water from the buffer tank, and have the boiler only serve the buffer tank. You could play around a bit with the temperature settings on the buffer tank so that it delivers reasonable hot water performance AND keeps up with the space heating load. Assuming the real heat load is 40,000 BTU/hr (probably high, but maybe), with 169' of baseboard that's 40,000/169'= 236 BTU/hr per foot, which can be delivered at an average water temp of 130F. So if you set the tank temp to 140-150F it'll cover the space heating load just fine, but the boiler only fires when the average temp in the tank temp drops 7-10F below the set point (this can be increased if necessary). The thermal mass of the water in the tank and the temperature swing of the tank determines the minimum firing time, which is quite a bit longer than the cycling it would be doing with just a single smaller zone calling for heat.

Radiant.jpg



The potable hot water heats up instantly as it's drawn through the heat transfer coils in the buffer tank. At 88,000 BTU/hr you have more than enough burner output to support a 24/365 shower (providing you can stay awake that long! :) ), and at a tank temp of 150F you don't need a monster-sized buffer to fill a normal sized tub.

But before going down that road, get the controls figured out, and start timing the burns when say, just the kitchen zone is calling for heat, or some other zone. If it's under 5 minutes (probably is) it's slipping in efficiency. If it's under 3 minutes it's probably worth doing something about it.
 

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How big is the house? (total square feet, by floor)

Does the boiler have an internal heat exchanger for the domestic hot water, or does it heat up a water tank parked next to the boiler, operated as it's own heating zone?

In 1971 almost all framed homes in the US were 2x4 studs with R13 or R11 batt insulation.

By "balance" I'm referring to how fast the heat can get out of the baseboards into the room relative to how fast the boiler is putting heat into the heating system. The hotter the baseboards, the higher the rate of heat (BTUs ) get emitted into the room. The boiler can't run hotter than about 220F at it's maximum (the maximum boiler temperature is something that can be adjusted on the boiler controls) and if it's putting 220F water into the baseboard the temperature along the baseboard drops as heat is lost to the room, so the temperature of the water returning to the boiler is lower, typically 20F lower. So the maximum average water temperature you're able to achieve is about 210F. A typical baseboard specification for how much heat it can emit across a range of average water temperature can be found here.

Most systems are set up for 170-190F max boiler temperatures, for average water temps of 160-180F. Running it hotter is somewhat less efficient than cooler temps, since there is more heat lost in the distribution plumbing and standby losses at the boiler itself, overheating the boiler room. But at lower temperatures it will short-cycle more often if there isn't sufficient radiation to emit that heat at the lower temperature, which takes an even bigger toll on efficiency. In your case you have more boiler output than any one zone can emit at any operating temp. In these situations you can usually lengthen the burn cycles somewhat and lower the number of cycles by retrofitting smarter controls than the CGa series comes with.

With these types of economizer controls it "exercises" the available thermal mass in the system (basically, all the system water and the boiler's cast iron content) across a wider temperature range when cycling to lengthen the burns, stops the burner slightly ahead of when it senses that the thermostat is soon to turn off the call for heat, and doesn't start the burner until it has extracted the most heat possible from the thermal mass of the boiler, dropping it's temp to wherever you program the low-limit to be (130F is safe for gas boiler.) Whether that will work in your case depends on just how short the burn cycles are. The dumb aquastat controls that come with traditional boilers like the CGa typically only swing a range of 10-25F, but an economizer control can deliver 70F swings or even higher- it makes a difference on the numbers of cycles when serving undersized radiation.

If the hot water is from an embedded coil inside the boiler it usually takes a 150-170F low limit to deliver reasonable hot water performance, which also limits what you can get out of smarter controls, but if it's an indirect tank you can still run the boiler down to 130F, giving you the full range of temperature swing.
 

Joann provetto

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Hot water tank parked next to boiler

Total sq ftg is 1800.

I found the floor plan from when we purchased so this shld be accurate


Basement 924 sq ft
1st floor 1025 sq ft
2nd floor 740.

it s a cape so there is no "attic" and sloped ceilings in master but not in other bedroom upstairs.

. The basement is not walk out is finished except for the boiler area (24 x 14 ft) which is not finished.

I was able to locate the sticker on the boiler. It says 105 btus. I even contacted Weil Mclain and they couldnt tell me size even with model number. Needed some other CP bar code number. Nuts. Thanks
 

Joann provetto

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Hot water tank parked next to boiler

Total sq ftg is 1800.

I found the floor plan from when we purchased so this shld be accurate


Basement 924 sq ft
1st floor 1025 sq ft
2nd floor 740.

it s a cape so there is no "attic" and sloped ceilings in master but not in other bedroom upstairs.

. The basement is not walk out is finished except for the boiler area (24 x 14 ft) which is not finished.

I was able to locate the sticker on the boiler. It says 105 btus. I even contacted Weil Mclain and they couldnt tell me size even with model number. Needed some other CP bar code number. Nuts. Thanks

I assume a "burn" is when the boiler is actually running?

This is kind of fascinating. And shows you have to have the right people working on your house.
 

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At 105 MBH (= 105,000 BTU/hr) input, at ~83-84% efficeincy that's ~88,000 BTU/hr out, so it's probably the CGa-4 (or equivalent.)

Yes "burn" means "burner firing". The pumps will be running continously whenever any thermostat is calling for heat, but the burner will be going on & off whenever just one thermostat is asking for heat since the limited zone radiation is delivering the heat at a slower rate than the burner is putting heat in. Putting more heat in than the radiation is pulling out causes the system temperature to rise. When the temp hits the boilers high-limit the burner turns off, but the zone pump will still be pumping water through the boiler as long as the thermostat is asking for more heat. When enough heat is pulled out of the boiler by that circulating water that temperature hits the low-limit, the burner re-fires. It's the duration of burner firing that we're interested in, especially when just one zone is calling for heat.

With only ~1800' above grade and ~1000 below grade I'd expect the heat needed at +15F for the above grade portion to be about 28-30,000 BTU/hr, and if the basement is NOT insulated it could be worth another 10-12,000BTU/hr, for a design heat load of about 40,000 BTU/hr for the whole house. If the basement IS insulated it'll be more like 30-32,000 BTU/hr. This is a WAG, not a load calculation- there are houses of that description that leak so much air that the load is 50,000 BTU/hr and similar houses with total loads of 25,000 BTU/hr.

Is there any insulation at all behind the finished walls of the basement (or the unfinished boiler room part)?

Either way there's no way the house needs anything nearly as big as the CGa-4. In that boiler series it's either the CGa25 (likely) or the CGa-3 (probably oversized.) But even legit plumbers bonded & licensed will make the same stupid mistake, not to make any excuses for the unlicensed hack who installed the thing, only to point out that 2-3x oversizing for the load is rampant in the industry, and few will take the time to run a heat load calculation (or even know how to do that properly.)

For yuks, take a look at Weil McLain's cheezy none-too accurate way-oversizing load estimator. You have ~3" of insulation in the walls and probably more that 6" in the attic, and double-pane windows, so you're roughly "construction design number" 8 or 9 in Table A for the above grade 1800', which they estimate at 43,190 BTU/hr at a 70F inside to outside temperature difference. Your 99th percentile temperature bin is +15F, so at 70F indoors that's a 55F difference. Multiplying by their scaling factor in Table C, thats 0.78 x 43,190 BTU/hr= 33,688 BTU/hr for the above grade house. Even if you allowed a whopping 15,000 BTU/hr for the basement losses that's still less than 50,000 BTU/hr. Which would put you in the CGa-3 according to Table-E.

I didn't bother doing the first floor & second floor factors for you, but there's just no way it's going to hit 50K even using that silly estimator. Mind you, these really crude calculators typically oversize by at least 25%, often more than 35%. I'd be suprised if the CGa-25 would ever leave you cold, even during Polar Vortex events when the overnight lows dipped below 0F. With the CGa 25's 44,000 BTU/hr output, even the 51' baseboard zone (which is the smallest) can deliver well over half the boiler output at an average water temp of 180F, which means it can be set up to deliver pretty reasonable burn times, and less than 5 burns per hour even when serving a single zone.

There are better online load calculators if you really want to get into it, but it doesn't much matter unless you're actually going to swap the boiler, which is a pretty expensive solution (unless you can make the jerk who installed it cover that cost.)

With a 71 gallon indirect tank you can fill a large soaker bathtub with no problem at all, and still have hot water left over. That means the boiler can (and should) be sized for the space heating load- no need to upsize for hot water service.
 

Joann provetto

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At 105 MBH (= 105,000 BTU/hr) input, at ~83-84% efficeincy that's ~88,000 BTU/hr out, so it's probably the CGa-4 (or equivalent.)

Yes "burn" means "burner firing". The pumps will be running continously whenever any thermostat is calling for heat, but the burner will be going on & off whenever just one thermostat is asking for heat since the limited zone radiation is delivering the heat at a slower rate than the burner is putting heat in. Putting more heat in than the radiation is pulling out causes the system temperature to rise. When the temp hits the boilers high-limit the burner turns off, but the zone pump will still be pumping water through the boiler as long as the thermostat is asking for more heat. When enough heat is pulled out of the boiler by that circulating water that temperature hits the low-limit, the burner re-fires. It's the duration of burner firing that we're interested in, especially when just one zone is calling for heat.

With only ~1800' above grade and ~1000 below grade I'd expect the heat needed at +15F for the above grade portion to be about 28-30,000 BTU/hr, and if the basement is NOT insulated it could be worth another 10-12,000BTU/hr, for a design heat load of about 40,000 BTU/hr for the whole house. If the basement IS insulated it'll be more like 30-32,000 BTU/hr. This is a WAG, not a load calculation- there are houses of that description that leak so much air that the load is 50,000 BTU/hr and similar houses with total loads of 25,000 BTU/hr.

Is there any insulation at all behind the finished walls of the basement (or the unfinished boiler room part)?

Either way there's no way the house needs anything nearly as big as the CGa-4. In that boiler series it's either the CGa25 (likely) or the CGa-3 (probably oversized.) But even legit plumbers bonded & licensed will make the same stupid mistake, not to make any excuses for the unlicensed hack who installed the thing, only to point out that 2-3x oversizing for the load is rampant in the industry, and few will take the time to run a heat load calculation (or even know how to do that properly.)

For yuks, take a look at Weil McLain's cheezy none-too accurate way-oversizing load estimator. You have ~3" of insulation in the walls and probably more that 6" in the attic, and double-pane windows, so you're roughly "construction design number" 8 or 9 in Table A for the above grade 1800', which they estimate at 43,190 BTU/hr at a 70F inside to outside temperature difference. Your 99th percentile temperature bin is +15F, so at 70F indoors that's a 55F difference. Multiplying by their scaling factor in Table C, thats 0.78 x 43,190 BTU/hr= 33,688 BTU/hr for the above grade house. Even if you allowed a whopping 15,000 BTU/hr for the basement losses that's still less than 50,000 BTU/hr. Which would put you in the CGa-3 according to Table-E.

I didn't bother doing the first floor & second floor factors for you, but there's just no way it's going to hit 50K even using that silly estimator. Mind you, these really crude calculators typically oversize by at least 25%, often more than 35%. I'd be suprised if the CGa-25 would ever leave you cold, even during Polar Vortex events when the overnight lows dipped below 0F. With the CGa 25's 44,000 BTU/hr output, even the 51' baseboard zone (which is the smallest) can deliver well over half the boiler output at an average water temp of 180F, which means it can be set up to deliver pretty reasonable burn times, and less than 5 burns per hour even when serving a single zone.

There are better online load calculators if you really want to get into it, but it doesn't much matter unless you're actually going to swap the boiler, which is a pretty expensive solution (unless you can make the jerk who installed it cover that cost.)

With a 71 gallon indirect tank you can fill a large soaker bathtub with no problem at all, and still have hot water left over. That means the boiler can (and should) be sized for the space heating load- no need to upsize for hot water service.

The unfinished part of the basement has poured concrete walls, no sheetrock. The finished part is sheetrocked. I have no idea if it is insulated. I think I see some I insulation around where the BB attach to the walls. It is pretty toasty down there, but that may be because it is underground basically.

Just out of curiosity, do people oversize because they don't want to be "caught short" so to speak. Better over than under?

The electrician showed up today to take a look. Even my dire description did not prepare him for what he saw! he said cant say he has ever seen that kind of wiring. Wired wrong. Realized today that the "mother board" for lack of my correct description where it shows you what the temp is does not turn on unless the basement therm is on. There are all kinds of relay switches etc. he is going to install a master switch.

I wish I could get the first guy to pay for this but that would involve suing him and I just cant invest that energy.

What is disheartening is that I reported him to our county consumer affairs. They are well aware of him. he has multiple complaints. He often does not even renew his restricted plumbers license yet they continue to allow him to work here let alone installing boilers when he is not licensed to do so and he is a bully. he threatened to sue me when I asked for my deposit back for the replacement of the basement baseboards that we finally figured out were not broken. Only after I took him to small claims did I get my money back AND on a payment plan! I certainly did not get a payment plan. This crummy job that I now have to pay more money to fix cost me over 8000 k. I could scream.
 

Dana

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Both contractors and homeowners have a propensity to err toward oversizing "just in case" without actually doing the math on either their heat load, or the amount of heat they could ever get out of their radiation. And that propensity BAD for both comfort & efficiency, and it's absolutely the wrong thing to do. ASHRAE recommends holding the line at 1.4x oversizing, no more.

Your probable load of something like 35,000 BTU/hr @ +15F, and your heating / cooling balance point is about 65F (it might be a bit lower, but not lot lower). The difference between the balance temp and the design temp is then (65F-15F=) 50F. Heat load increases fairly linearly with temperture difference, so that 35,000/50F= 700 BTU/hr per degree below 65F.

With an 88,000 BTU/hr output boiler you're good for 88,000/700= 126F heating degrees, which means that if you have enough radiation you can keep the place at 70F indoors all the way down to (65F - 126F= ) -61F.

That is a temperature not seen on Long Island since the last ice age, and a temperature that you won't see most years even in Fairbanks AK.

If you instead had the smallest of that line with half the output (the 44K output CGa-25), you're only good for about 63 heating degrees, so you'd be able to keep it 70F indoors at +2F (fully 13F below your 99th percentile temperature bin) but you'd be slipping a bit at lower temps if it stayed much lower than +2F for more than a few hours. That might happen once in 25 years, but it might not. Worst case is you turn down one zone to be able to keep the zones you care about up to temp. Most of the time you wouldn't even notice it.
 
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