I'm a homeowner in downstate NY. My 15 year old electric water heater is starting to leak periodically, and needs replacement.

I'd like to replace it with a gas tank heater for lower fuel costs, and it seems Bradford is a reliable brand. While researching the costs of a Bradford with a power vent, I came across a new old stock Combicore M2-C-TW75T10CN unit for $1000.

In my area a 40gal NG heater from Home Depot is $400, and the local supply house quoted me a 50gal NG heater with power vent for $800.

For space heat I have a 1976 Burnham gas boiler with 3 zones of baseboard. It works ok, but it can't quite keep up on the coldest days of 0-10F. My 1500sqft 1961 split level has single pane windows, poor insulation, and cathedral ceilings. My heat loss is probably roughly 65-75kbtu with a 70F delta.

My question is:

If I'm spending $700-800 on a water heater, does it make sense to get this Combicor unit for $1000 and use the heat exchanger as the primary heat source for my baseboard heating, keeping the Burnham for backup? Can it even be done in a simple way?

I'm thinking that even with only 82% efficiency the CombiCor would be better than the Burnham, and that the two units can be plumbed in parallel with a manual power switch and zone valve to keep the Burnham out of the loop 95% of time. I don't have a problem flipping a switch manually to bring the Burnham online on days when the CombiCor can't keep up. Since that would only be 5% of the time, it seems that they could just share the heating load 50/50 with no fancy balancing, just a Y junction in the heating loop.

I can commit to $1000 plus 3-4 hours of plumbing but not much more.

Thanks for your input.

If you really have a heat loss of 65-75,000 btuh, you'll come up short by 15% or more with the combi, as that is its INPUT not its OUTPUT:

http://www.blueridgecompany.com/documents/combi_water_heat.pdf

www.heatpro.us energy businessmen's knowledge

Yes, you really have to find out the MAKE and MODEL to get good answers. There IS more than one machine made.

Thanks for your reply. I figure I'll need to run the Burnham for back up on the coldest days.

Are there any fundamental problems with doing a setup like this?

I'd like to know if these combi units have really been used satisfactorily for replacing conventional boilers.

Thanks,

Putting boilers in parallel is a normal commercial practice.

Yes, many things have worked.

www.heatpro.us energy businessmen's knowledge

Yes, you really have to find out the MAKE and MODEL to get good answers. There IS more than one machine made.