Combined hydronic/DHW on demand with atmospheric vent through flue for small apt?

Jells

I have small 450 ft rental apartments currently hydronically heated by their 40 gal DHW tanks. I'd love a better solution, but the last one installed before these was a Minitherm boiler with an indirect tank that was awful. It was noisy, undependable, and created a ridiculous amount of interior heat in summer. I cannot use a direct vent because the building is an attached rowhouse, I have a flue.

A local heat contractor I just spoke to said there are "wall hung" units that can fit the bill, he mentioned Utica but could not recall a model. Needless to say the contractor is currently overwhelmed dealing with emergencies and has no time for my issues. Does anyone have any ideas, pointers recommendations?

hot_rod

Bradford White has a few versions of the CombiCor, a tank with internal coil for hydronics.

http://www.bradfordwhite.com/combi-1-atmospheric-vent-system

Jells

Thanks Hot Rod, but that's what I'm trying to get away from! Specifically the relatively short life and low baseboard temps.

hot_rod

what are the heat emitters, baseboard?

Tough to find a boiler small enough for 450 sq. ft? Probably a load around 8,000 - 10,000 BTU/hr?

Jells

Hot Rod, I kinda just asked that question in my other thread on my current specific problem. Your guess is right on, the place currently has 9520 btu@140deg in baseboard, and that has been sufficient for 6 years and 2 tenants till the current cold spell. This is why I thought keeping the DHW heater feeding the baseboard with 40k btu was a pretty good plan for now. I've caught some crap for not using an exchanger, and I'll be correcting that, even though both my heating contractors poo-poo the Legionella thing. One thinks I'm an idiot for using a mixing valve and a high setpoint on a whole house 75 gal WH.

hot_rod

I think a lot of marginally designed heating systems are being put to the test this winter.

Also the structures tend to deteriorate over the years, weather stripping hardens, door seals wear, batt insulation can settle, infiltration goes up, heating load along with it.

Makes one wonder how design temperature is selected for various areas.

Gordy

hot rod said:

I think a lot of marginally designed heating systems are being put to the test this winter.

Also the structures tend to deteriorate over the years, weather stripping hardens, door seals wear, batt insulation can settle, infiltration goes up, heating load along with it.

Makes one wonder how design temperature is selected for various areas.

Myself also. In my area in my life time I have seen lows in the -27 range at quite a few times. Design is -9.....