Boiler location in a basement closet?

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Dana

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Soil is more porous than you think. Sub-slab depressurization should be taking most of it from the soil. If the slab has cracks or isn't well sealed at the edges some of it can come from the house, but those can be sealed with self-leveling polyurethane caulk or a more heavy-bodied polyurethane caulk formulated for good adhesion with concrete /masonry. Sealing the slab improves the effectiveness of the radon fan, and is usually/often one of the first steps taken by radon remediation contractors. Any cracks in the foundation wall should be caulked in a similar fashion prior to installing wall insulation and finishing the walls.

When the slab and foundation is starting to get pretty tight it's often possible to hear a subtle hiss at the remaining leak points, if it's otherwise quiet in the basement.
 

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Soil is more porous than you think. Sub-slab depressurization should be taking most of it from the soil. If the slab has cracks or isn't well sealed at the edges some of it can come from the house, but those can be sealed with self-leveling polyurethane caulk or a more heavy-bodied polyurethane caulk formulated for good adhesion with concrete /masonry. Sealing the slab improves the effectiveness of the radon fan, and is usually/often one of the first steps taken by radon remediation contractors. Any cracks in the foundation wall should be caulked in a similar fashion prior to installing wall insulation and finishing the walls.

When the slab and foundation is starting to get pretty tight it's often possible to hear a subtle hiss at the remaining leak points, if it's otherwise quiet in the basement.

Right. the walls and floors are without cracks--I'm quite fortunate in that way, especially for an old basement. So I think the main source is from the three sump pump openings. I know that it's doing its job partly because whenever I remove a sump cover, there is a hiss from the suction. There is also a suction indicator on each of the four lines that shows the presence of suction. I could turn off the line that goes to the kitchen crawl space, or just install a shutoff valve to reduce the amount of air pulled from it. The crawl space is covered with thick plastic and under it there is a perimeter loop of 1.5 inch pvc with air holes to withdraw any radon escaping from the ground. I've always been skeptical about the usefulness of that loop. And a 200 cfm fan seems rather large, but may not since it pulls from four sources. I'm seriously considering replacing it with a 100 cfm unit. I find it interesting that the plants within 24" of exhaust point have all died. Maybe it's from radon, or maybe the exhaust air dries them out. I hope it's just the latter.
 

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Installing air tight sump lids and sealing other large openings in the slab is pretty much job-1 for radon mitigation in my area! Ground vapor barriers in crawlspaces etc get mastic-sealed to the foundation along the perimeter too.

Soil gases are full of all sorts of less-savory stuff, not just radon. It takes a LOT of radiation to actually kill plants- does your house glow in the dark? :) The drying theory is probably correct.
 

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Installing air tight sump lids and sealing other large openings in the slab is pretty much job-1 for radon mitigation in my area! Ground vapor barriers in crawlspaces etc get mastic-sealed to the foundation along the perimeter too.

Soil gases are full of all sorts of less-savory stuff, not just radon. It takes a LOT of radiation to actually kill plants- does your house glow in the dark? :) The drying theory is probably correct.

Wow!!!! I can't believe that I've come to this point!!!-- but all this discussion has prompted me to seriously consider replacing my existing boiler with 1 or 2 condensing boilers. I still can't believe that I'm actually saying this.

Some considerations are:
1. The condensing unit boasts higher efficiency
2. Properly sizing the boiler(s) to a lower Btu (approximately 100000 Btu versus 200000 Btu) may lead to even more efficiency.
3. I installed a Rinnai tankless hot water heater a couple years ago using a concentric intake/exhaust, and I assume that installing 1 or 2 similar boilers for heat will be a similar effort at the boiler end. That is, this seems like a DIY project.
4. My existing system outputs through 3" black pipe that hangs down about 15" below the basement ceiling. The newer boilers seem to use 1" pipe, and I can easily drill a hole for that in the middle of each joist, giving me a full ceiling height.
5. The condensing units take less space and eliminates fireproof wall considerations.

My questions are:
1. Should I consider installing a single larger boiler--about 110000 to 120000 Btu, or 2 smaller boilers that would enable 2 zones?
2. Should I consider using pex for the hot water output line, or stick to black pipe, or consider cpvc, or something else?
3. Does it make a difference which brand I select (see price comparisons at bottom of attached sheet)?
4. I'm surprised at the price of a controller for the Rinnai, and I assume that each manufacturer requires their own pricey controller. Is there a cheaper way to get around buying one for each boiler?
 

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Reach4

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Maybe it's from radon, or maybe the exhaust air dries them out. I hope it's just the latter.
It's not radon.

I have a hard time thinking that air drawn like that would have much lower humidity than the outside air.

I don't have an explanation for the die-off.
 

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Wow!!!! I can't believe that I've come to this point!!!-- but all this discussion has prompted me to seriously consider replacing my existing boiler with 1 or 2 condensing boilers. I still can't believe that I'm actually saying this.

Some considerations are:
1. The condensing unit boasts higher efficiency
2. Properly sizing the boiler(s) to a lower Btu (approximately 100000 Btu versus 200000 Btu) may lead to even more efficiency.
3. I installed a Rinnai tankless hot water heater a couple years ago using a concentric intake/exhaust, and I assume that installing 1 or 2 similar boilers for heat will be a similar effort at the boiler end. That is, this seems like a DIY project.
4. My existing system outputs through 3" black pipe that hangs down about 15" below the basement ceiling. The newer boilers seem to use 1" pipe, and I can easily drill a hole for that in the middle of each joist, giving me a full ceiling height.
5. The condensing units take less space and eliminates fireproof wall considerations.

My questions are:
1. Should I consider installing a single larger boiler--about 110000 to 120000 Btu, or 2 smaller boilers that would enable 2 zones?
2. Should I consider using pex for the hot water output line, or stick to black pipe, or consider cpvc, or something else?
3. Does it make a difference which brand I select (see price comparisons at bottom of attached sheet)?
4. I'm surprised at the price of a controller for the Rinnai, and I assume that each manufacturer requires their own pricey controller. Is there a cheaper way to get around buying one for each boiler?

It's almost never cost effective to install two boilers when one can do the job. With a 10:1 turn down ratio an HTP UFT-120W (or the Westinghouse labeled version of the exact same boiler, distributed through Home Depot in some states) can vary it's output from about 11,400 BTU/hr to 114,000 BTU/hr. Even at 120F it only takes 65' of baseboard to emit the full 11.4K. A Lochinvar WHN111 would be pretty similar, modulating between 10,500 - 105,000 BTU/hr.

But it probably doesn't even need to be that big. I suspect the fuel use load calc on the house as-is/as-was prior to improvements is going to come in at about 80K, and after insulating the basement and doing more air sealing it'll be in the 70K range, which would make an 80-85K input fire tube boiler with a 10:1 turn-down ratio a reasonable choice, 100-105K max.

It's not impossible to install a UFT-xx boiler as a DIY, but study up on hydronic systems (a LOT) before diving in. That series comes pre-plumbed with a separate port to support an indirect water heater, but with the shiny new Rinnai already in place there's no reason to go there. Understanding the min & max flow requirements for both the boiler and system radiation is important to making this work. It's way more than just a plumbing exercise, and it's probably worth have a hydronic design professional spec the system, including all the pumps, valves, etc even if you do the work.

In your boiler list you're using net water output numbers where you SHOULD be using the DOE output numbers, since it's all inside of conditioned space. eg: The Weil Mclain ECO 110 has a DOE output of 101,000 BTU/hr, not 88,000 BTU/hr.

The ECO 110 is a nice boiler, but with only a 5:1 turn-down ratio, which means it takes about twice the amount of radiation the similarly sized WHN 111 or UFT 120W to keep it from short cycling on the basement zone. Minimum firing rate is as important as maximum when sizing a modulating condensing boiler, especially when there are low-load or minimal radiation zones to deal with.
 
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Jadnashua

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Most of the condensing boilers use pvc pipe for both air inlet and exhaust where the exhaust must have proper slope to it to allow the additional condensate to drain back to the pump, and then be expelled somewhere (keep in mind, the condensate is acidic...you may want to neutralize it, depending on where it is dumped). Those with a lower efficiency may require SS lines, and only the lower efficiency ones need a standard flue.
 

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It's almost never cost effective to install two boilers when one can do the job. With a 10:1 turn down ratio an HTP UFT-120W (or the Westinghouse labeled version of the exact same boiler, distributed through Home Depot in some states) can vary it's output from about 11,400 BTU/hr to 114,000 BTU/hr. Even at 120F it only takes 65' of baseboard to emit the full 11.4K. A Lochinvar WHN111 would be pretty similar, modulating between 10,500 - 105,000 BTU/hr.

But it probably doesn't even need to be that big. I suspect the fuel use load calc on the house as-is/as-was prior to improvements is going to come in at about 80K, and after insulating the basement and doing more air sealing it'll be in the 70K range, which would make an 80-85K input fire tube boiler with a 10:1 turn-down ratio a reasonable choice, 100-105K max.

It's not impossible to install a UFT-xx boiler as a DIY, but study up on hydronic systems (a LOT) before diving in. That series comes pre-plumbed with a separate port to support an indirect water heater, but with the shiny new Rinnai already in place there's no reason to go there. Understanding the min & max flow requirements for both the boiler and system radiation is important to making this work. It's way more than just a plumbing exercise, and it's probably worth have a hydronic design professional spec the system, including all the pumps, valves, etc even if you do the work.

In your boiler list you're using net water output numbers where you SHOULD be using the DOE output numbers, since it's all inside of conditioned space. eg: The Weil Mclain ECO 110 has a DOE output of 101,000 BTU/hr, not 88,000 BTU/hr.

The ECO 110 is a nice boiler, but with only a 5:1 turn-down ratio, which means it takes about twice the amount of radiation the similarly sized WHN 111 or UFT 120W to keep it from short cycling on the basement zone. Minimum firing rate is as important as maximum when sizing a modulating condensing boiler, especially when there are low-load or minimal radiation zones to deal with.

I like the WHN111 even though it seems pricier than the Weil Mclain or Rinnai. I guess it costs more because of the 10:1 turn-down ratio? From what I've been reading, it looks like I easily can get two zones from one boiler by installing a zone valve.

All the lines to the 1st and 2nd floor radiators are fairly accessible from the basement ceiling, and I look forward to replacing the existing 3" iron piping with something smaller that goes through the floor joists. Is 3/4" and 1" oxygen barrier pex flexible enough to easily feed through the middle of the joists, or is this going to be super difficult? I notice that the outlet pipe from the WHN111 uses 1". I'm wondering if I could simply use two manifolds, one to serve the 1st floor and basement, the other for the second floor and third floor, and then run 3/4" lines from the manifolds to each radiator? However, five of the lines to the second floor are actually branch lines that feed radiators stacked on both the second and third floors. So I assume that the lines going to those branches should be at least 1" to handle the volume required for two fairly large radiators (sized for 27,000 Btu and 33,000 Btu). Those five branch lines currently use 1-1/4" black iron pipe.
 

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The HTP UFT-100W and 120W are pretty cheap (cheaper than a cast iron boiler that size), as is the Westinghouse labeled version. They are manufactured by a first-tier Korean boiler & water heater manufacturer, Kiturami.

Balancing room temps with home-runs from a zone manifold to each individual radiator is an endless task. If the room to room temperature balances on each floor seem pretty decent, zoning it floor by floor using much of the existing distribution plumbing will probably work. (Let's not steal a defeat from the jaws of victory here!)
 

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The HTP UFT-100W and 120W are pretty cheap (cheaper than a cast iron boiler that size), as is the Westinghouse labeled version. They are manufactured by a first-tier Korean boiler & water heater manufacturer, Kiturami.

Balancing room temps with home-runs from a zone manifold to each individual radiator is an endless task. If the room to room temperature balances on each floor seem pretty decent, zoning it floor by floor using much of the existing distribution plumbing will probably work. (Let's not steal a defeat from the jaws of victory here!)

Right. The room temperatures on each floor and each room seem fairly well balanced with the existing boiler and lines.

I can see two ways for me to plumb the replacement system:
1. Option 1 would simply replace the existing single large 3" black iron loop around the perimeter of the basement (that serves all the radiators on all 3 floors) with two replacement loops, loop 1 for zone 1 serving the first floor and basement, and loop 2 for zone 2 to serve the second and third floor. With this design, I may not even need a manifold, but would install two replacement loops of 1" or 1-1/4" pex, each loop feeding the radiators on a zone. Essentially, each loop would serve as a manifold. So the design would look somewhat similar to the existing system, except that I would use a couple of zone valves to open or close each zone (loop).
2. Option 2 would feed two manifolds located next to the boiler, manifold 1 for zone 1 serving the first floor and basement, and manifold 2 for zone 2 to serve the second and third floor. Like you said, however, this would require home-runs to/from each manifold. I assume that 3/4" pex could be used for lines that feed individual radiators, and 1" pex would be used for the lines that feed branches of multiple radiators. And like you said, the result may or may not feel balanced.

It seems that you recommending Option 1?
 

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Right. The room temperatures on each floor and each room seem fairly well balanced with the existing boiler and lines.

I can see two ways for me to plumb the replacement system:
1. Option 1 would simply replace the existing single large 3" black iron loop around the perimeter of the basement (that serves all the radiators on all 3 floors) with two replacement loops, loop 1 for zone 1 serving the first floor and basement, and loop 2 for zone 2 to serve the second and third floor. With this design, I may not even need a manifold, but would install two replacement loops of 1" or 1-1/4" pex, each loop feeding the radiators on a zone. Essentially, each loop would serve as a manifold. So the design would look somewhat similar to the existing system, except that I would use a couple of zone valves to open or close each zone (loop).
2. Option 2 would feed two manifolds located next to the boiler, manifold 1 for zone 1 serving the first floor and basement, and manifold 2 for zone 2 to serve the second and third floor. Like you said, however, this would require home-runs to/from each manifold. I assume that 3/4" pex could be used for lines that feed individual radiators, and 1" pex would be used for the lines that feed branches of multiple radiators. And like you said, the result may or may not feel balanced.

It seems that you recommending Option 1?

Although the room temperatures seem balanced, the balance between the 1st and 2nd story could be a little better-- our 2nd floor usually feels 2-3 degrees warmer than the 1st. I think that results from the open stairwell between the two floors, letting the heat naturally rise to the second. So maybe two zones would help correct that?
 

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In most homes zoning floor-by-floor usually works better than running multiple floors as a single zone. So if the room to room balance on each floor is fine, zoning by floor will likely fix it.

Basement zones are the worst, since the changes in heat load of a basement aren't nearly as big as that of above grade floors.
 

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In most homes zoning floor-by-floor usually works better than running multiple floors as a single zone. So if the room to room balance on each floor is fine, zoning by floor will likely fix it.

Basement zones are the worst, since the changes in heat load of a basement aren't nearly as big as that of above grade floors.

Please help me to evaluate the Rinnai E110SRN (104000 Btu output) versus the Lochinvar WHN110 (102,ooo Btu output). I understand that the Rinnai is a 5:1 turn-down while the Lochinvar is a 10:1 turn-down. However, the Rinnai costs $1400 less, at $2260. Since my existing total winter bill is a little less than $2500, it will take longer to break even for the Lochinvar. I assume that either system will be about 15% more efficient than my present system, and the replumbing and dual zone addition may save another 5-10% for a total savings of about 25% ($600/year). Assuming re-plumbing costs of about $1000, this makes about a 5.5 year payback for the Rinnai system (total cost = $3260). This is still cost-effective. So how much more per year will the 10:1 turn-down save me versus the 5:1 turn-down?
 
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Looking at it as the net present value of future energy savings is all wrong. Finding the right boiler for the load that will work, and not be a royal PITA to maintain, and last a long time is more important. The additional radiation necessary to keep from short-cycling the boiler is also part of the up-front cost, that doesn't appear in the simple price of the boiler hardware.

At ~$2000 the HTP & Westinghouse 10:1 turn down fire tube boilers in that size range are substantially cheaper than the Lochinvars, and probably cheaper than the Rinnai, and simpler to install than most boilers.

And before we even get to that we need to get a much better handle on your actual heat load. Let's pick apart some gas bills, and make some educated guesses on how much the effects of oversizing have exaggerated the fuel use based heat load measurement, and how much more heat load is likely to be peeled off in the air-sealing & insulation efforts, etc.

It's also important to re-examine your EDR numbers an in particular the load /EDR ratio for each room to come up with the water temperature requirements. Condensing boilers typically top out at 180F water out, but if it has to be plumbed primary/secondary (as is often the case with high flow radiation) you might not be able to get more than 170F water out of the hydraulic separator, 160F average water temperature through the radiation, which according to the nomograph in the radiator sizing document means about 130 BTU/hr per foot EDR. If it's marginal or clear you need more than that, it can be an issue that affects boiler choice and system design.

As previously mentioned, hydronic design is more than just a plumbing project.
 

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Looking at it as the net present value of future energy savings is all wrong. Finding the right boiler for the load that will work, and not be a royal PITA to maintain, and last a long time is more important. The additional radiation necessary to keep from short-cycling the boiler is also part of the up-front cost, that doesn't appear in the simple price of the boiler hardware.

At ~$2000 the HTP & Westinghouse 10:1 turn down fire tube boilers in that size range are substantially cheaper than the Lochinvars, and probably cheaper than the Rinnai, and simpler to install than most boilers.

And before we even get to that we need to get a much better handle on your actual heat load. Let's pick apart some gas bills, and make some educated guesses on how much the effects of oversizing have exaggerated the fuel use based heat load measurement, and how much more heat load is likely to be peeled off in the air-sealing & insulation efforts, etc.

It's also important to re-examine your EDR numbers an in particular the load /EDR ratio for each room to come up with the water temperature requirements. Condensing boilers typically top out at 180F water out, but if it has to be plumbed primary/secondary (as is often the case with high flow radiation) you might not be able to get more than 170F water out of the hydraulic separator, 160F average water temperature through the radiation, which according to the nomograph in the radiator sizing document means about 130 BTU/hr per foot EDR. If it's marginal or clear you need more than that, it can be an issue that affects boiler choice and system design.

As previously mentioned, hydronic design is more than just a plumbing project.

OK--that all sounds good to me.

I'm finding this fun, and want to continue with this education. Tomorrow AM I leave on a week-long trip, so I'll definitely want to pick up and learn more about this when I get back. Thanks for all your input. You've spent a lot of time helping me to understand the issues.
 

Jadnashua

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A 3" iron pipe has a huge capacity. Replacing the runs with small pex and a manifold with its much higher head may be problematic. Your overall water volume would likely change as well. Lots of things to consider in that swap.
 

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A 3" iron pipe has a huge capacity. Replacing the runs with small pex and a manifold with its much higher head may be problematic. Your overall water volume would likely change as well. Lots of things to consider in that swap.

I think I understand the value of a condensing boiler and the value of high turn-down ratios when used in a single zone system, but I don't understand how this works for multiple zone systems. My understanding is that the boiler is always in the "on" position when used with zones, and the zone valves simply shunt the hot water in one direction or the other. That is, the system uses outside air temperature, not inside, to determine the turn-down. So:

1. Does the system ever shut down completely?
2. If the system is always "on" it seems that it would be wasting fuel if neither zone is calling for heat?
3. If the system uses only outside air temperature, it seems that the system would not know what turn-down is needed?

My understanding of the basic theory and function is lacking when applied to a zone system.
 

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A 3" iron pipe has a huge capacity. Replacing the runs with small pex and a manifold with its much higher head may be problematic. Your overall water volume would likely change as well. Lots of things to consider in that swap.

Just for fun, I calculated the gallons of water in the present system. The radiators have a total of about 351 gallons in them. The main-loop line in the basement has 56' of 3" pipe, 40' of 2" pipe, and 20' of 1.5" pipe. The return line is the same length, but about two-thirds is 2" pipe and the remaining is 1.5". I think this totals about 50 gallons in the main-loop line and return. And there is about 4o more gallons in the lines between the main-loop and the radiators. Naturally, replacing the boiler will reduce the size of the main-loop line by at least 50%, but the radiators and branch lines to them will remain untouched. So it will probably only save about 25 gallons.
 
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Jadnashua

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I think I understand the value of a condensing boiler and the value of high turn-down ratios when used in a single zone system, but I don't understand how this works for multiple zone systems. My understanding is that the boiler is always in the "on" position when used with zones, and the zone valves simply shunt the hot water in one direction or the other. That is, the system uses outside air temperature, not inside, to determine the turn-down. So:

1. Does the system ever shut down completely? Yes, when no zone is calling for heat (including an indirect, if installed), the system can get to ambient - IOW, it does not always run.
2. If the system is always "on" it seems that it would be wasting fuel if neither zone is calling for heat? See above, it is not always on.
3. If the system uses only outside air temperature, it seems that the system would not know what turn-down is needed? Many of the better systems have an outside temperature sensor that, when programmed properly, can adjust the output temperature to best accommodate the load. They generally, also look at the return temperature to make the assessment of how hot they should get.

My understanding of the basic theory and function is lacking when applied to a zone system.
 

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I need a sanity check for my heating figures.

In the attached spreadsheet, you will notice the EDR and calculations on the Btu output and water volume for each of my hot water radiators. The Btu output and water volume look high to me. For instance, the “Entry” radiator has an EDR of 6.3 (it is 23” high and 5 tubes), and includes a total of 26 sections. I’m showing this will output 27846 Btu. Wow, that seems like a lot for a single radiator!

Moreover, if you look at the second page of the attachment, you will see that this same radiator should hold 25 gal of water. Again, that seems like a lot of water for one radiator. Are these calculations really right, or am I figuring something wrong?

If these calculations are right, then my existing system (see second page of attachment) holds 575 gallons. That seems incredible. It’s more than I can believe unless someone else can verify that I’m figuring things correctly.
 

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