Need help on deciding residential heating

9 years ago

last modified: 9 years ago

Purchased a home (approx. 2200 sq. ft.) in New England that we’re (husband and I hired GC) are in the process of renovating. The house was built in 1950 with an addition in 1972. The heating is a mix of oil fired hot water convectors and baseboards in the old/newer part of the home with a total of 4 zones. High velocity AC (Unico) was added in 2012. Our original contractor removed the original faces of all of the convector units, discarded them, and subsequently walked off the job. We just found a new, reputable GC.

Now we are left with deciding whether to convert convector units to baseboard heat (total of 7 units) and keep the 4 zones powered by the boiler, or remove all baseboards and retrofit the air handler for the AC unit in the attic with a hot water coil to handle heat, also powered by the boiler in the basement. However, this would effectively put us on a 1-zone heat system. A couple of notes to consider:

1. One baseboard is located under a window that we’d eventually like to convert to sliding doors to a future deck, so regardless we’d likely consider moving this baseboard to another exterior wall
2. We’re not sure if a boiler pushing 1 hot water pipe to the attic is more efficient than generating hot water for baseboards located throughout the home. Does anyone know which would be more expensive to operate?
3. If heat coming from the ceiling is inefficient. One HVAC subcontractor mentioned that 1 zone could make the 1st floor cold while another thinks the high velocity nature of the system would push heat effectively to the 1st floor. For the basement, half of it would be heated while the other half would not.
4. If we kept baseboards we’d have to reroute some heating pipes as some of them are running along the exterior wall, and also some of the baseboards were damaged during demo.
5. Some hot water pipes for baseboards run into an unheated crawlspace beneath the addition, and they have some type of foam insulation on them.

Any thoughts/suggestions/opinions would be much appreciated. I'm happy to provide more information if you need it. Also the house is currently gutted so we wouldn't need to rip out walls to remove old hot water pipes if we went to forced air.

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Comment (1)

ionized_gw
9 years ago
It may be very difficult to make home comfortable with a single zone. It depends on how different the relative heat requirement change with time of day, sun-derived radiant heat and season. Lots of hydronic heating systems were chopped up into zones in an attempt to limit fuel use when oil prices spiked. Now, some are being recombined into fewer zones make them run better with modulating, condensing boilers. The gain from zoning can be marginal anyway with poorly-insulated homes.

I have some comments that speak to efficiency and the type of delivery device. Fin-tube aluminum convectors need higher temperature water than radiators. Hydronic coils sometimes use even higher temp water. (The hotter the water, the smaller the coil.) With condensing boilers you need low temperature return water to use the boiler in any way efficiently. The differing delivery devices can be combined to get good efficiency, but you need to find someone that knows what they are doing. With a complete gut you must be greatly upgrading insulation and air sealing. You need less emitter to heat with now and a smaller boiler. If you keep the emitters on the high side, however, you can run with lower water temp and preserve the efficiency of the boiler. A lot of engineering goes into the designs.

Enclose the pipes in the crawlspace in a way that couples them to the living space above and insulate the outside of them while removing the insulation between the pipes and the space above. Insulation around the pipes themselves is OK.

This is a great forum, but there are not a lot of hydronic heat/boiler heads posting here. There are more at terrylove.com and at heatinghelp.com, "the wall".
laurasteiger thanked ionized_gw
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