Advice on Hydronic Heating


Old 01-24-15, 08:53 AM
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Advice on Hydronic Heating

Good morning everybody! First time poster. Let me start by saying this forum is absolutely great. The expertise and knowledge that Iv'e seen while reading through thread after thread is amazing. When I had my taco swetchek valve banging, I came here. When I wanted to know boiler pressures and temperatures, I came here. When I needed to know about auto fill, and bleeder and flow control valves, I came here. That being said, I figured if I were to join any of the forums and ask a couple questions, this would be it! So thanks again!

I have lived in Mass in a stucco/cement single story (with full unfinished attic, and basement) for about 3 years. The house is slightly under 2000 sq feet with 2 bedroom additions included in that square footage.

The first addition was built in 1958 and is 16x18. It is on a slab. It has R13 insulation between the ceiling and a flat rubber membrane roof. The walls are block walls with stucco on the exterior and framed/sheet rocked on the interior with R5 rigid insulation on the block and R13 on between the bays of the framing. It is fed from the boiler through black iron pipe and then transitions to o2 barrier pex, and then to approx 28' of slant fin copper baseboard. The return is o2 barrier pex which I insulated, and then transitions back to the black iron to return to the boiler. The heat is only on in this room at 66 from 5-630am when the wife and I are getting up and going to work. Other than that it is set to 60. This is zone 1.

The second addition was built in 1985 and is a 10x12 wood framed stucco exterior with sheet rock interior and R13 in the walls and ceilings (hip roof, not much pitch). It also sits on a cement slab. This room has approx 18' of copper baseboard I didn't install. The feed and return are all copper to and from the boiler. The heat is set to 55 on 3 days of the week, and when the step son is home after school is goes up to 66 until bed time when it goes to 60. This is zone 2.

The main house was built in 1937 and is actually poured concrete with a stucco exterior finish. It has approx 7 cast iron radiators fed and returned with black iron pipe. It originally had 8 (there was one in the unfinished full attic, but I took that out hoping to save money and capped the pipe). It also has a 6 foot run of cast iron baseboard in the bathroom fed and returned by 1/2" O2 barrier pex (the copper lines were damaged when I removed it to refurbish it). There is no air in the the radiators or baseboards and they all heat up nicely. This zone kicks on when people are home after work and school up to 68 and goes to 60 when everyone is away or sleeping. There is no insulation in the walls and there is a 1/4" to 1/2" air gap between the inside of the concrete siding and the 1x6 tongue and grove sheathing that frames the house. The interior walls are 1" plaster. Balloon frame, basement to attic. There is old cellulose blown in insulation up in the attic. This is zone 3.

I have an older (70's 80's?) Slant Fin Galaxy GG-175. AGA Input BTU/Hr 175,000. Capacity BTU/HR 140,000. Water BTU/HR 121,700. What is the efficiency of this particular unit? The feed leaves the boiler through the top. From my research it is a 2 pipe, direct return system (the first radiator fed, is the first returned). The Circulators are on the return side. Zone 1 and 3 have old B&G 1/6HP pumps, and Zone 2 has a grundfos UP 15 42 FR. All of the circs have their own ancient looking aqua stats that go along with them.

Heres the issue.. Over the past 3 years after all the improvements I've done which include, all new windows, more insulation in walls, filling cracks and gaps, caulking and sealing, having the house painted, etc.., I still can't bring the winter monthly gas bills under 400$ They are usually between 4-500 for Dec, Jan, Feb. Obviously November and March are in the 300 dollar range.

I do plan on getting 3 new draft free exterior doors and adding more insulation to the attic in the spring. Obviously the boiler does not have an outdoor reset (after reading all about boiler temperature and outdoor resets on here), so I lowered it from 195 to 180 hoping that would do something. Taking the radiator out of the unused cold attic doesn't even seem to have done anything either. I figured that was good hot water that was going up there and cooling more, dropping the temp in the boiler when it returned. Insulating the feed and return piping doesn't seem to do much either.

I am hesitant to add any blown in to the walls because the house was designed to be able to 'sweat', hence the air gap left between the inside of the siding and the wooden framing. After much caulking, and sealing, and painting to get rid of a water intrusion issue, the last thing I was is something like a mold issue.

My question is, should I go out and bite the bullet and get the high efficiency buderus boiler Iv'e been looking at? Would it even work with the hodgepodge of piping and mixture of radiator/baseboard that I have? Would I see a dramatic decrease in my heating gas bill if I went with a 95%AFUE unit? Could anybody think of anything else I may want to try first? I appreciate all your input! Thanks
Do I have to worry about primary secondary piping issues? Like I said, I have a 2 pipe direct return.
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Old 01-24-15, 08:58 AM
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I forgot to mention, I think this system is too big.. Not sure but it kicks on like 5-6 times an hour for like 5 minutes a time.
Old 01-24-15, 09:09 AM
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What is the efficiency of this particular unit?
Conventional boiler, probably in the low 80s.

the circs have their own ancient looking aqua stats
Probably RELAY controls rather than aquastat.

I still can't bring the winter monthly gas bills under 400$ They are usually between 4-500 for Dec, Jan, Feb. Obviously November and March are in the 300 dollar range.

How can this be? Could your heat loss possibly be that high?

I'm going to say that while replacing the boiler MIGHT save some... there's something else going on for your gas bills to be that high.

Perhaps an 'Energy Audit' with a blower door test is in order to see where your heat is going.
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