Adding Bradford CombiCor Makes Sense??

dr2

I'm a homeowner in New York.  I need a new water heater, and am thinking of changing from electric to gas.  Bradford water heaters seem to have positive reviews.  While investigating the Bradford line, I came across the M-2-C-TW-75T10CN, which has a 60,000 btu space heating exchanger combined with a tank heater for about $1000.



For space heat I have an old (1976) Burnham gas boiler feeding 3 zones of baseboard heat.



Since I'm thinking of spending $750 on a NG tank heater (with power vent), it seems beneficial to get this slightly more expensive unit, and use the (hopefully more efficient) CombiCor 60,000 btu as my primary space heating source, backing it up with the old Burnham during the extra cold days.



Am I missing anything basic by considering this approach?  My objective is to minimize my water/space heating costs and investment, but also to get the most from what I do spend.



I'm roughly estimating my heat loss at 100,000 btu on a 70F differential for my 1961 1500sqft split level with single pane metal frame windows, cathedral ceilings and 3" insulation.



Thanks for your input.

Jean-David Beyer

I am not a professional, but ...

... will this not result in a system more complex than what you might wish?



Instead, why not get a mod|con boiler and an indirect-fired hot water heater.

Probably have the water heater at high priority. Have outdoor reset on the boiler for the home heating. Then you do not need to have to heating units and the complexity to synchronize them.



I do not know about doing this gradually, such as adding an indirect hot water heater to the existing boiler, but a professional should know.

dr2

Complexity is relative

Thanks for your reply.  My constraint is the budget, I'm afraid.  I'm in for $750, and can push that to $1000.  I'm thinking that a new furnace with HW supply is going to start at a budget of $5000.



The complexity issue could come out of this as a part of the answer from the pros, but I'm thinking that on my current Burnham I have a setup which looks like this:  baseboard return into the burnham, hot water out of the burnham, circulator pump driving the water around, and 3 zones valves in parallel.



In the simplest approach, I would hope to put a T in the baseboard return to feed the Combicor exchanger, and put a zone valve and a T after the burnham to feed Combicor heated water into the system, with the ZV preventing flow thru the burnham.  Put a power switch on the burnham and ZV to turn it off and on depending on if the house room air is reaching target temp or not.



During times when I need the Burnham, I agree the flow would not be optimized, with half the flow being heated by the Combicor, and half the flow being heated by the Burnham, but this would be only on the coldest of days, maybe 10-15 per year.



My estimate of heat loss is likely overdone by 30-40% as well.



BTW I am completely ready for someone with real world experience to tell me what I'm missing here, so feel free to jump in.