What's Your Maximum Boiler Output Temoerature?

[Donl]

I'm curious to see how high others are setting their boiler output temperatures. Indicate whether or not you have storage. If so what type(pressurized, non pressurized epdm liner?)

This is the first year I have used storage (500 gallon propane tank) and have increased my o/p temp from last year to about 90 degrees C (194 F). So far the storage is working very well, but I'm temped to increase boiler o/p temp even higher to get longer heat recovery periods. One observation I have made with the increased temp in my EKO is that it seems to run much better. i.e. no sticking door, no damper opening by itself, and a good steady burn.

Don

 

[Singed Eyebrows]

Atmos wants their boilers to be set at 85 C with the thermostat(this switches the fan on & off) & at 90 C on the Samson. The Samson is there as a safety. I run normally 80 to 83 C. I have pressurized storage. As I understand it my cooling loop thermal solenoid opens at 94 C so Im not in a hurry to run high temps. I have no creosote problems with this boiler, Randy

 

[Nofossil]

Theoretically, you'll get somewhat better efficiency at lower outlet temps (cooler water surrounding the fire tubes). I drive my outlet temps pretty low (60 - 65 C) if i'm heating DHW or the hot tub, or heating a cold storage tank. I'll use 75-80 if the baseboard zones need heat. As storage temps ramp up, I'll increase my outlet temps to stay 5 degrees above the top of storage as long as I can.

If you don't wan't to be that [del]fancy[/del] obsessive I'd use the lowest outlet temp that gives you acceptable results - maybe higher when you want to get more out of storage.

 

[kabbott]

I have my variable speed control set up on the bypass and boiler loops now and I run the return at 160 and the outlet at 185. I have
an EDPM lined tank and only run it up to 185. My heat exchanger won't quite keep up to my new boiler so when the tank nears 180 or so
the boiler pump is at 100% and the temps creep up over 200. I am considering going to a propane tank and I would not think twice about
going to 200-205F. Much more starts to scare me, 1000 gallons flashing to steam would not leave much house left!

The Varmebaronen seems to burn better when hotter, but I really have not burned enough to know what is more efficient.

Kris

 

[Chris Hoskin]

kabbott, in our experience 185 is a bit too hot for an EPDM lined tank. If I remember correctly, STSS is recommending 170 on their tanks. Not that the tank will fail catastrophically at the higher temps, but you may start to seeing weeping through the liner inside ten years. At the lower temps an EPDM liner could last twice that long.

Don L I like where you are at now, I just get a little worried if you have a boiler chugging along at 200+ degrees F and the power fails.

Chris