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Sunny H
Antique house - replacing furnace

What type hot air heat would be best for my 175 year old house? I must replace my oil hot air furnace immediately. I will be using the ducting in my house now. I want to put in A/C, also.

Natural gas is not available. Propane is a possibility, but I hear it does not produce as much heat as oil, although I know a gas furnace is more efficient than oil.

I am looking at:
1. a plenum system like the one I have now - burner heated hot air ( very dry). Might need a humidifier. The only problem is our water corroded our last one(s), even though I have a Culligan water treatment system.

2. a hydronic system of hot air heat - a boiler with hot water pipes to heat air blown across them. The air is not so dry, but the cost is far more than the other system.

I have been told by every local heating business that a geothermal heat pump system would not work because old houses leak too much air; so apparently, that's out. And, heat pumps would need a back up heating system in my area. As for climate, I am located near the ocean and near NYC.

Do I pay more for the expensive hydronic system or go with the less expensive traditional plenum system?

Re: Antique house - replacing furnace

A Geo-thermal system is a heat pump that is supplied with about 52% degree water regardless of the outside temp. Sizing the system to your house may not be cost effective.

The hydronic system you describe has a serious flaw, any time you do a heat transfer from one medium to another you have the cost of the loss. No system is 100% efficient.

You already have duct work and you want AC. When we changed from oil to propane we lost the smell of the oil, soot on the roof, and half the heating cost. If it were me I would install an 80% efficient unit. The cost savings in fuel for a 90+ unit is offset by initial cost and increased maintenance costs. You should be able to get a humidifier that will work with your water.

Sunny H
Re: Antique house - replacing furnace

I have been told that new oil furnaces are all about 80 - 83% efficient. Gas run 93 - 95% efficient, which is better; however, propane gas is quite expensive and prone to fluctuations in price, so that worries me. Also, it does not give the same BTU's that oil delivers, so I would have to use more propane than oil to get the same level of comfort. I keep seeing numbers that people run and propane heat is always more than oil.

We have never had any oil smell, nor soot on roof. I just am not happy about buying oil from the middle east :( I'd prefer geo thermal, which I actually know quite a bit about, but it won't work effectively in my 175 year old house as it has too many air leaks.

Anyone know anything about the difference between the comfort levels of plenum and hydronic hot air systems? My architect and several heating contractors have recommended the hydronic over the old fashioned plenum, but it is much more expensive. Thanks

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