Options for updating both heating and cooling

dwilliams123

So I recently inherited an older home that is lost in time. Still has the original 1951 gas furnace, 186K BTU, with returns on the outside walls and gigantic ducts everywhere. At some point, an AC air handler was cobbled on to the furnace, using the original heating ducts. The system heats pretty well when it's on, but of course the gas bills are outrageous, and the system cools poorly in the summer even when it runs full-time. Natural gas here is considered reasonably cheap though, and electric somewhat more expensive. Western Pennsylvania.

The house is a two-level ranch, 1600 SF main floor and 900 SF conditioned basement.

I myself am partial to radiant, but a subfloor retrofit would be too much to go into. I was thinking about radiators instead of all the ductwork. Because of the layout, a ductless system would probably need 4 units through the walls.

Just curious what people here feel would be the best way to go from here. Thanks.

Jamie Hall

It's rare for an A/C add-on to a forced air system to work well -- particularly older ones. The ducts are likely to be too small (regardless of your comment that they are gigantic!) and the supplies and returns not well placed.

That said...

The least expensive option is going to be to replace that elderly furnace. Not that I have anything against elderly, but newer ones are a lot more efficient. I wouldn't care to say how much that would cut your gas bill -- but it could be impressive. That wouldn't do much for your air conditioning, though.

You should also make sure that envelope upgrades are done to the extent you can -- insulation, storm windows (not necessarily new windows -- they are somewhat overrated in comparison to good storm windows), that sort of thing. That will help both the heat and the A/C.

Another alternative would be a ductless minisplit system. Depending on just how cold it gets, that might just do the whole job, if the interior heads were placed well. It's worth looking at.

dwilliams123

The HVAC people who have seen the system have all said the ducts are too big and incorrectly placed, and should all be replaced. I don't want to put in a completely new forced air system, I was considering either hot water radiators, or a ductless system. Was wondering if there was an upside or downside to either.

Jamie Hall

Incorrectly placed I'll buy. Too big? Ah... no. Quite possibly poorly balanced. But not too big. All that would do is reduce velocity, which reduces losses and noise. I think your HVAC folks are looking for work.

I will say that if they really are over size by modern standards, there's a chance that they are big enough for air conditioning -- which would simplify matters. Changing register placement might be a bit of a challenge, depending on how things are arranged. You might be able to put in a central heat pump/air conditioning system.

But you are going to need a creative contractor.

JUGHNE

First thing is to do a heat loss/gain calculation.
Certainly over sized furnace now by a factor of at least 2.

One item that worked well for change outs was to use the existing heat run/grills on the inside walls for cold air returns.
Then cut in floor registers on the perimeter for supply.

But hot water radiators or wall panels would be a lot more comfortable with individual room thermostats.
Then Minisplit heat pump/AC for cooling and shoulder season heating are the best of both worlds.

dwilliams123

I've lived with radiators before, and I really liked them. If I need to replace the entire system, I'd rather go with hot water radiators. They're not common in my area though. Not sure if any drawback compared to hot air.