Condensing boiler or Cast iron??

[NY_Rob]

The article linked above mentions the use of "Boost" feature when some setback is still desired.
The HTP UFT has the Boost feature, and it's very flexible with quite a few options.

(from the HTP UFT-80W install manual):

Boost Function:
When Outdoor Temperature Mode is used, Boost Function increases the CH
set point temperature by the Boost Degree temperature [10:bd]) at time
intervals (Boost Interval [11:bI]). A space heating demand must be active
without a DHW demand over the Boost Function set period of time (9:bt) for
boost to activate. Boost continues until the boiler reaches the maximum supply
temperature set point (6:cH) based on the outdoor reset curve. The boiler will
return to normal operation after the thermostat is satisfied.
Range: 0 - 120 min
NOTE: “0” means boost function is OFF.


Boost Degree:
Sets the temperature added to the boiler target set point based on the Outdoor
Temperature Mode reset curve.
Range: 5 - 15F
Default: 10F


Boost Interval:
Sets the interval time when the boiler will increase the temperature by the Boost
Degree. Ex: Initial Boost: 10F. After 20 MIN Interval: Boost will increase CH set
point temperature another 10F. After another 20 MIN Interval: Boost will
increase CH set point temperature another 10F. This will continue until the
boiler reaches the maximum supply temperature set point (6:cH) based on the
outdoor reset curve, or until the thermostat is satisfied.
Range: 0 - 120 MIN
Default: 20 MIN

 

[Dana]

Since you have sufficient radiation on each zone to run in condensing mode without short cycling, there isn't a good rationale for the additional complexity & expense of adding a buffer tank. Buffer tanks can sometimes make sense when house has been micro-zoned to death, but that's not your house. In cases where some zone or another doesn't have sufficient radiation, it's often cheaper & easier to add more radiation rather than a buffer tank to fix any short-cycling issues. You can end up spending a lot of money squeezing the last 1% of condensing efficiency out of a system, saving what, $10-15 per year? In your situation you'd likely be better off applying buffer tank & micro-zoning money on blower door directed air sealing & spot insulation, or toward rooftop solar PV.

If you want to add a zone and heat the garage, go ahead, but it should be a separate zone. The heat loss characterisitics of a garage differ quite a bit from typical conditioned space of a house, and the room temperatures wouldn't balance well if simply added to a zone. Just be sure that it has enough radiation to not short-cycle on that zone at condensing temps. For the UFT-080W that takes about 30-40' of fin tube baseboard, which is less than $500 if you shop around.

The sheet metal on fin-tube tends to get banged up pretty quickly in a garage, and the fins accumulate dust pretty quickly. You can probably re-use some craigslist cast iron radiators, and come in at lower $, and have a bit of thermal mass to limit short-cycling.

With rads you 'd only need ~150 square feet EDR to balance perfectly with the min-fire output of the UFT-080W at condensing temps if heating the garage to fully 68-70F, but with the thermal mass and the likely lower room temp you'd be looking for in a garage 100' EDR would usually more than cover it. Low profile Sunrad/Radiant 5" x 20" x _?? " convecting cast iron radiators run 1 square foot EDR per foot of length, so even 8-10' of those would be enough to keep from short cycling, and probably enough to cover the heat load of the garage. (They're pretty hefty, about 5lbs per 2-1/4" wide section, or about 2.25lbs per inch of running length, but with a 3/4" plywood ramp and a couple of furniture moving dollies and some half-inch rope I moved a 58 incher by myself in an SUV, and I'm no Hulk Hogan. It took some belay rigging, more ramp for the stairs and a come-along to drag it from the basement to the second floor by myself after cleaning it up & re-painting. They were pretty popular in NY/NJ up through the early 1960s, when cheaper fin tube convectors and baseboards took over the market, and wouldn't be totally out of place in a circa 1966 house the way antique column radiators might.

 

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[hammer49]

Your point well taken. According to my supplier FW Webb in Newburgh says the HTP UFT 080w is not available any more is this possible? If so I need to find something just like it .murphys law.

 

[Dana]

HTP still has it up on their e-commerce site- I'd be quite surprised if they're pulling it. You can always call their toll-free number to find out for real:

800-323-9651

The Westinghouse badged version is still available online from web stores.

 

[hammer49]

Thanks Dana I called HTP myself and they said they do still have that boiler it's just my supplier doesn't carry it so I have to go to Emerson Swan to get it they are the carriers for New York .Reading another post of yours about ECM smart pumps I find that very interesting with zones valves instead of circulators. I'm pretty handy and mechanically wise I'm wondering if I can install this myself .I work in the construction trade so I know how to do electric and plumbing. I know the basics of plumbing and heating . If I had a diagram of how to plumb it,where to put special valves and and y clean out and what ECM pump to buy with the right GPM flow,and what is ever else is needed I could do this.but it my lack of that knowledge of what I need is what stops me.my friend is a plumber who installs air-conditioning and heating but is not fine-tuned on con modulating boilers that's what scares me. When I present questions to him on things I've learned of this site he doesn't know the right answer.Am basically teaching him what I learned.

 

[Dana]

Long time hydronic heating designer Morgan Audetat (BadgerBoilerMN ) would be able to spec every valve & pump in the system for you (for a fee), and is intimately versed on the merits of the UFT-080W having just installed one, if you wanted to take a shot at a DIY installation.

 

[hammer49]

Ok maybe badgerboilermn can contact me or pm with his fee information.thank you again

 

[Dana]

Ok maybe badgerboilermn can contact me or pm with his fee information.thank you again

Or you can email him directly.

 

[hammer49]

My system now.i did the hot water heater and water softener.

 

[hammer49]

Looked on badgerboilernm site he don't support 100 percent DIY. WARNING: If you are 100% DIY, we cannot help you with condensing boiler or water heater installations since you are likely to hurt yourself and others.so I have to look else where .Thanks to everyone for all there help I learned a lot.

 

[Dana]

Even if not 100% DIY, having a fully specified design and the hardware in hand allows you do bid it out competitively.

 

[hammer49]

So I had a plumber come over and look at my house and didn't recommend that I'd get a modulating condensating boiler because some rooms might not get as hot on real cold days and my water is hard and I have a water softener so he recommended to stay with a cast-iron boiler with a power vent he recommended a Dunkirk but from what I read some people don't like them. So does anybody have any ideas of a 80,000 BTU cast-iron boiler that they would recommend.
Thanks

 

[Dana]

Did the guy run a heat load calculation on those rooms, and measure the radiation and calculate the peak temperature requirement, demonstrating peak temp below the ~180F upper limit of the average mod con?

If not, discount his opinion- it has no basis.

What makes you think you need an 80,000 BTU boiler? Even the worst-case analysis on the fuel use demonstrates a load of ~40,000 BTU/hr at your outside design temp, with a more likely load closer to 35,000 BTU/hr. The biggest cast iron boiler you should install on that system should be 1.4x the actual load (per ASHRAE), which would have an upper bound of (1.4 x 40K= 56,000 BTU/hr, but a more likely upper bound of (1.4 x 35K=) 49,000 BTU/hr. That would reliably cover the load coldest hour of the past 50 years in your location with some margin.

With 144' of baseboard and the worst-case 56K estimate that works out to 56,000 /144= 388 BTU/her per foot. With typical baseboard, that can be delivered an an average water temperature of ~150-155F. The maximum output temp of the UFT-080W (and most other mod-cons) is 180F, and it would have NO problem delivering the full 56,000 BTU/hr of heat into the house.

In short, your plumber doesn't appear to be a hydronic designer or true heating specialist.

If some room or rooms doesn't have sufficient radiation for it's load and always runs cool, at $10-15/foot it's not very expensive to upgrade the radiation. And if you wanted to treaty some rooms for extra comfort, installing a panel radiator with a tweakable thermostatic valve to raise or lower that room's temperature relative to others isn't a huge expense either.

If all else fails and you really MUST go with cast-iron, go with a mid-efficiency sealed combustion direct vented type (which lowers the actual heat load relative to atmospheric drafted boilers), such as the Burhnam ES2-3. That boiler delivers 52,000 BTU/hr (/40,000 = 1.3x your worst cast calculated load, and /35,000 = 1.5x your likely load), and it would hit its nameplate efficeincy AFUE if set up properly. Side venting it would be comparable to or cheaper than 85% efficiency chimney drafted boiler of similar output, since it trades the cost of a full-length chimney liner necessary to provide the necessary draft to manage flue condensation. By going direct vented you can seal up the old flue, getting rid of the 24/7 parasitic heat load of the induced outdoor air infiltration that the flue would otherwise drive.

But it's probably going to be cheaper to install the UFT-80W than a Burnham ES2-3, since the raw cost of the boiler is lower, and the CPVC venting is cheaper.

 

[hammer49]

Thanks again Dana I have to look for some more plumbers because no one seems to know what their talking about.and no he didn't do a design heat load of the house .when he looked at my system he said it was wrong the circulators should not be on the return side of the boiler. It's worked fine for years like that. I posted pictures of it what do you think is he right?

 

[Dana]

Whether on the supply or return side of the boiler, it's best practice to place the expansion tank on the entering side of the circulators, which reduces cavitatation at the impeller and other associated issues, some of which can affect the longevity of the circulators. With multiple circulators this isn't always possible, and there are many systems plumbed the way yours is that deliver decades of service, despite being less than ideal.

With higher pumping head boilers (= not cast iron boilers, but some modulating condensing boilers) it's best practice to install the expansion tank near the output side of the boiler, followed by the circulator, pumping toward the usually higher pumping head of the distribution plumbing & radiation:

Fire tube heat exchanger type mod-cons (like the UFT series) have comparatively low pumping head (=flow resistance) relative to other types of condensing boiler heat exchangers, but even if you install one of those it's probably the right time to address how the circulator or circulators are plumbed relative to the boiler and expansion tank.

With a mod-con's outdoor reset curve dialed in correctly to the load the circulator(s) will run nearly continuously. With most systems it makes more sense to use a single highly efficient "smart" ECM drive pump, and do the zone control with zone valves. But it takes a hydronic designer who can do the math to properly spec the pump and how it should be set up. This is a different set of skills than many "heating & plumbing" contractors have within the company, though some do. Talk to the badger. Having proper hydronic design specified from the get go (even if implemented by another heating & plumbing contractor) is a lot cheaper and more satisfactory than fixing it later. With a full design package in hand it can be bid out competitively.

 

[hammer49]

Thanks Dana for your advice I think you're right having the proper hydronic design is best and then work from there.