Questions for the pros

16 years ago

Getting ready to install new heat pumps to replace other systems. I do own the one-story houses but they are not my primary residence. One is about 850 square feet, has oil furnace, no AC, installed about 1953. Uninsulated ducts in basement with supply registers on the inside wall, returns on the outside walls, at least one of supply and return in each room. One contractor proposes switching supply/return functions of the existing registers, retaining their locations and replacing the duct work with properly sized and insulated ducts. I like that idea. The other proposes using the outside wall locations for the new supply and then cutting just one return IN THE FLOOR for the entire house and just abandoning in place the interior wall previous supply registers which are cut into the baseboard and would be lots of carpenter work to remove. I like that idea much less. I think the first proposal will give better distribution in each room. No prices yet on either proposal.

The other involves a gas furnace and central AC. The outside unit sits on a concrete patio. Contractor says the code will not permit siting the heat pump unit on the concrete as winter defrost water can freeze on the concrete and create walking hazard. Sounds plausible to me. Other contractor did not mention this at all. But the present unit location is under kitchen window and about as far as possible from any bedroom. His suggested location is under one of the bedroom windows. I think I might just tear up the majority of the concrete, about 400 square feet, 5 cubic yards, and keep the unit under the kitchen window.

Being as lengthy as you wish, please give me your suggestions.

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Comment (1)

maryland_irisman
16 years ago
Bus Driver,

The first guy appears to have a better handle on what should be done. If I got what you said right, he has determined those outside wall ducts are sized and distributed properly to be used as supplies. You also mentioned he will install properly sized ducts.

A good design would have the supplies on the outside wall since that is where infiltration would most likely take place. The supplies would form an air curtain on those walls, giving more comfort.

I am not a fan of whole house returns. As you already suggested, you'll get better distribution pressures and control if you have individual returns.

As for location of the condensing unit, if it has to be near a room, the kitchen would be much better than a bedroom. Noise factor would be the issue. Even if the unit isn't a noisy one, it can be disturbing when the lights are out and everything else is turned off.

As you know from your own skills, every location has it's own rules. The melting ice when in the heat pump mode can create an issue when it refreezes on the slab.

My suggestion is, if you can have the unit mounted on a raised stand, that would help keep deeper snows from surrounding the coil, preventing air flow. I would not suggest having it raise-mounted attached to the building. Even though there are noise dampeners, it can still transmit vibration and noise into that wall. This is especially true over time, when the rubber mounts harden and wear. If you tear up the patio and pour a slab for the condensing unit, don't let the slab touch the building.

Since you are having a complete install, is it possible to have the furnace positioned in the center of the basement? This would be the most optimum location for the unit, especially for air distribution and balancing.

I hope I've helped some!!
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