heat exchanger or not?

Warren Licht

Dear Mr. Holihan:

I have a heating problem. Most of the house is steam, except the basement baseboard and sunroom - hot water. The heating problems apparently started after the last owners built a 3rd floor master suite and added baseboard hot water. The master suite is too high above the boiler and often "freezes up" from air pockets in the water line; the basement and sunroom are smaller zones, only 8 feet above the boiler on the sunroom zone and seem less of an issue. Separate from "freezing up", the heat of the rest of the house (steamed areas) is often 10 degrees hotter in order to heat the 3rd floor to 65 degrees.

From reading your site, it appears that a heat exchanger and active circulator may be my solution.

Questions:

Can I use the aquastat that I already have on the system?

Can I use the already existing "zones" and just add in the heat exchanger and circulator prior to the manifold of 3 zones already piped?

Who do you recommend locally that does this job well; most RI plumbers seem unfamiliar with this type of "system"?

Thank you.

Warren Licht

Warren Licht

heat exchanger or not


I have a heating problem. Most of the house is steam, except the basement baseboard and sunroom - hot water. The heating problems apparently started after the last owners built a 3rd floor master suite and added baseboard hot water off of the steam boiler. The master suite is too high above the boiler and often "freezes up" from air pockets in the water line; the basement and sunroom are smaller zones, only 8 feet above the boiler on the sunroom zone and seem less of an issue. Separate from "freezing up", the heat of the rest of the house (steamed areas) is often 10 degrees hotter in order to heat the 3rd floor to 65 degrees.

From reading your site, it appears that a heat exchanger and active circulator may be my solution.

Questions:

Can I use the aquastat that I already have on the system?

Can I use the already existing "zones" and just add in the heat exchanger and circulator prior to the manifold of 3 zones already piped?

Who do you recommend locally that does this job well; most RI plumbers seem unfamiliar with this type of "system"?

Thank you.

Warren Licht

DanHolohan

How high

above the waterline of the steam boiler is the highest point in the third-floor hot water zone?

Warren Licht

approximately 25 feet above the water line of the boiler

DanHolohan

It should work

This is from Heating Q&A (on the left side of your screen) under Condensate Hot Water Heating:

Q: But a 3/4" pipe is wider than a straw. Won't the water fall out of it?
A: Not unless air gets up into the zone. The principle is the same, regardless of the width of the pipe. At sea level, the atmosphere pushes down on everything with a pressure of 14.7 pounds per square inch. One pound per square inch can lift water 2.31 feet straight up, so, if you have a pipe that's sealed at the top and completely filled with water, the atmospheric pressure will be able to support a column of water about 34 feet high (14.7 psia X 2.31 feet = 33.957). It has to do with pressure, not the width of the pipe. Get it?

Does your hot water zone have a bypass to keep the water from flashing to steam when the circulator shuts off? I show the proper piping in the Heating Q&A section. Take a look.

Warren Licht

No there is no proper bypass to prevent "flashing" to steam, and I know this is necessary.

Also will there still be a temperature differential with a heat exchanger (i.e. hotter on the floors with steam radiators) when trying to heat the water zones with the heat exchanger system, and if so will it only be 1-2 degrees not 8-10 degrees like it is now?

DanHolohan

The bypass

should solve the problem. You shouldn't need water hotter than 180 F, and you can easily get that with the bypass in place. If you go with the heat exchanger you'll also need another circulator, more controls, a compression tank and a feed valve.