Problems with new hot water loop

Peter Rothstein

I recently added a hot water loop to a steam system (multiplate heat exchanger below the water line, pump circulated) and am having problems with the water side keeping up the temperature. Seems only to be able to keep a 40-50 degree differential from outside, which these days is a problem.

It's a series loop with the heating units teed off of the main, then piped directly to a separate return. The main is 3/4 inch, most of the heating units are supplied with 1/2 inch lines off of the tees which are oriented up. The circulator for the hot water loop is on the return right before the heat exchanger. First in line after the heat exchanger is a kickspace heater, then about 8' of baseboard, then two large 4' cased convectors. The convectors are in window seats (first I thought that might be the problem, so I opened up the window seats and removed the fronts so the convector cabinets are totally exposed to the room, but that didn't really change anything. The temperature in the large room (about 380sf.) where the cased convectors are is the lowest, it's at the end of the loop.

The temperature difference between the supply and return is only about 7 degrees, which seems way too low. Any ideas? I think that the tees to the kickspace and convectors are regular tees rather than diverter tees.

I'd appreciate any and all help! (The Wall was extremely helpful when I replaced my boiler, so I really appreciate the sharing of knowledge that goes on here!)

Thanks,

Peter R.

ta finnegan

Questions

Do you have any air elimination device in this circuit?

What are the total btu's you are suppling from this loop?

What is the size of the boiler?

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Peter Rothstein

re: questions

There are automatic air vents and manual bleeders. Not quite sure the total BTUs of the loop, I can try to figure that out.

Boiler is aW-M SGO 8 266K BTU Gross, 833 sq. ft steam, 200K BTU Net

The supply temperature is around 174-77 degrees and the return is around 167-70 degrees.

Does this help?

Thanks very much for replying!

nick z.

problems

Seems to me you might need diverter T's at least on the return side. Its my guess that since its coming off of a steam system that the circ. isn't making a hole lot of press. diff. in the loop. Rememeber the water will take the past of least rescitence.As Dan says see the water and be the water and it will help you. Good Luck!