Need advice

John_38

We recently moved into a 30 year old house with a 30 year old American Standard G-2 Gas Boiler. The boiler runs a three zone system controlled via TACO values. The system has a single BG Circulating pump (series 100) on the return side (not pumping away).

When we moved in, I put set back thermostats on the upper and main levels and set the thermostats to setback to 56 degrees at night, running 70 during the hours when the house is occupied. Unfortunately, during a January cold snap, the upper and main levels froze up so that no heat was getting through to these zones. Luckily the basement level continued to work. However, when the temperatures rose during the day, the upper level started to work again followed by the main level two days later. I dodged that bullet and have kept the setbacks at 70 degrees until a week ago when the sticker shock of the heating bill ($524.00) caused me to lower the temperature to 68.

Because of these problems, I had a contractor come over and look at the system and assess what my options are. He told me that we should repipe the system using smaller higher pressure themostatically controlled pumps (thereby achieving the desired pumping away affect). In addition, he wants to put on an Outdoor reset controller to setback the boiler temperature when the outside temperature warrants. Thirdly, he wants to have the new boiler also provide domestic hot water to the house.

I'm having some difficulty with using the boiler to create domestic hot water. Currently we have a brand new gas water heater supplying hot water to the house. I don't see any reason to replace it. The contractor was aware that the unit was brand new but thought having the boiler create hot water would be more efficient. Also even though the boiler is 30 years old, couldn't the TACO values be replaced with pumps or at least the circulating pump moved from the return side to the expansion side? It seems that this old boiler may have more life left in her and I could save a few bucks with these repairs rather than replacing it.

I'd appreciate any thoughts that other readers of the Wall might have. Thanks in Advance.

Jim Eastman

Sure, you could keep the old boiler and incorporate most of your contractor's suggestions. Ask for an option to incorporate manifold piping to convert to an indirect water heater at the time in the future when (1) the direct fired water heater craps out or (2) fuel costs of heating domestic water with the inefficient direct fired unit becomes painful, or (3) you put in a big soaking tub or jetted tub that the direct fired unit cannot fill.

Outdoor reset with some of the new modulating boilers is quite efficient and comfortable. You can do outdoor reset with your old boiler, but not as effectively as with some of the newer boilers. I don't see the need for zoning with circulators if the zone valves are doing the job. Perhaps there is a good reason for this recommendation that you haven't shared? Maybe you could have your contractor provide you with an estimated fuel savings and a payback ratio for the investment in the new boiler? It sounds like you are working with a knowledgeable hydronics person, so challenge him/her to answer your questions!

Jim Eastman

Joe_13

Great ideas, but

I don't think these improvements will help your gas bill that much when it gets real cold out. Pipes freezing durring setback probably means poor insulation and pipes going through unconditioned space. I would invest first in insulation/new windows and then have the boiler replaced after a heat loss calc was done to see if a smaller boiler will meet the heat loss. If the boiler is large enough and the house is well insulated, you could get the indirect tank down the road to replace the gas HW tank by puting it on priority, just get an outdor reset boiler control that has DHW priority function now like a Tekmar 260. Priority will shut off the heating zones for a short while to allow he boiler to service the indirect exclusively. Tighten up the house first or you'll be oversizing the boiler, causing it to short cycle when you do insulate.

Mark Hunt

Joe hits a homerun!


Look, we can carry a one million BTU boiler into your basement and you would NEVER be cold again, but you would also be poor.

Insulation and air sealing are cheap compared to a new heating system. Stop the BTU's from leaving and we won't have to replace as many.

When you lower the heat loss, we can lower the boiler size. YOU save money on both install costs AND monthly fuel bills.

Do it smart!

Mark H

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Wethead7

set back

Also do not set this unit or any other unit back past 5 to 10 degrees. The warm up will waste more heat than you save.