Proper water temperature for forced hot water heating system

[MPost]

Does anyone know the proper water temperature for a forced hot water (not steam) heating system? I seem to remember it's around 180 degrees, but just wanted to make sure.

Thanks

[Bubba]

It depends on whether you have cast iron radiation or copper fin tube radiation..........However, there really is no "one correct temp". You need only the amount of heat (temp) that will heat your home sufficiently. That number varies with the outdoor temperature. Thus, an indoor/outdoor reset control was born. Bubba

[willshak]

On 1/6/2005 7:53 PM US(ET), MPost took fingers to keys, and typed the=20 following:

It's around 180=BA F for a hot water system, but it can be a little more =

or less, depending upon the manufacturer's design setting. My oil fired=20 HW boiler is maintaining a 165-170=BA temp, but it's 20 years old and may= =20 be a little tired.

--=20 Bill

[barry]

It depends- meaning there's no "best" aquastat setting. (See Bubba's response.) The higher the setting, the higher the recovery rate because of the higher overall heat transfer rate. And ... the higher the setting, the lower the overall efficiency. (Consider the higher exhaust temp.)

Ignoring the additional circ-pump "exercise", the "best" setting could be that at which the system is barely able to hold house temp at t-stat set-point, with circ-pump running constantly.

In a previous house, I'd set it at 130 for fall/spring and 165 in Jan./Feb., though previous owner was almost running a steam-boiler. (Insulation/sealing are best means of heating.) Your mileage will vary.

John

[HeatMan]

Sounds like you're doing you own version of outdoor reset.

[MPost]

Thanks for the info. I have cast iron radiators and have the temp set at 140 degrees right now. It seems to be able to keep the house at a decent temperature with the circulator pump running about 50% of the time. I guess I'll keep it at that for now.

Thanks

[Steven Fleckenstein]

The manual for my Dunkirk Empire oil fired furnace suggests baseboard heating requires 200 degree temp water.

The installer had it set for about 170.

This was fine until we ran into teens and single digit cold weather with high winds. I had to nudge it up to 200 to keep this 16 year old home above 65 on the upper floor. R-19 walls / R-22 attic, Anderson narrowline double pane windows.

Steve

[Bubba]

Baseboard cast or copper fin tube? Maybe you dont have enough radiation in your home? Maybe your baseboard radiators have dirty fins, carpet too high blocking them, vents not open all the way or furniture blocking them? Turn it up if you need it, then turn it back down when the outdoor temps raise. Or get an indoor outdoor reset control Bubba