Homeowner with efficiency question

Dan_15

Hello, I am a homeowner and despite the inordinate amount of time I have spent reading these posts to learn about hydronics when I should be working, I continue to be confounded by efficiency. I have a Buderus G215 hooked up to an old converted steam heating system. Ive got 10 full-sized convectors in the house plus an additional three small ones in the bathrooms. All that water mass is moved by grundfos 3-speed circulator on the return side. The boiler is regulted with a simple Honeywell aquastat L8148A.

Can somebody explain in simple terms how water temp and circulator speed affect efficiency? I dont have outdoor reset, so I find myself dialing up the aquastat in the dead of winter (like tonight when its 5 degrees). But Im just shooting in the dark. I dont understand the basics. How does the circulator speed affect my efficiency? Is it better to dial up the temp very high and slow down the circulator? Or is it better to speed up and turn down the temp? Or both? Neither? Help!

Uni R

Efficiency

H-O to H-O, I'll give you my take. Since you don't have a condensing boiler, the sole thing your circulator does is distribute heat. Set your Grundfos to the slowest speed where the heat is even throughout the house. If you don't have small infrared thermometer ask Santa. That will quickly tell you how your heat is room to room compared with what you want.


As for your water temperature, get an outdoor reset. Either the Buderus control or something else. What you want is your water temperature adjusting itself to the exepected heatloss of the house. If it's colder outside, the water needs to be hotter. You can guess by setting it at 140 when it is fairly mild, 160 if it is really cold or higher if 160 won't keep your warm enough in a real cold snap. Having your water temperature set too high for the outside temperature just means that your rads go through wider temperature variations which reduces your comfort and can also make them noisy. Also, your boiler is sending more heat up the flue trying to get the water to a higher temperature than it really needs to.

Dan_15

Thanks for the primer. Well, I have turned up the circulator speed to hi, and now the upper rooms heat nicely. But the whole house now seems warmer, and the burner is cycling more often. Perhaps I will dial down the room thermostat a degree to reach a good overall comfort temp.

psd_3

Circulator speed has a huge effect on efficiency when it's not sufficient to put the heat where you need it. In other words you'll loose twice when the circulator speed is too slow ... the heat is spent in standby losses and you freeze. If the circulator speed is higher than is really required, you'll produce a bit more noise and you'll spend a few cents more per day in electricity. Error on the side of faster flow and spend your time understanding your heat load and tuning the aquastat to match demand.

The output temperature is definately more critical. Too little and you can't offset the heat loss. Too much leads to big temp swings, increased standby losses and significantly decreases efficiency.

Weezbo

you need the steam head control......

hes going to tell you the right scoop one time done deal

Dan_15

Where can I find the right scoop? All this advice makes good sense; is there something more to it?

Weezbo

click on the post above this one....

this guy is far more clayrvoiant at steam systems than i.sometimes he picks up on the simplest clue and He Really Really likes steam systems

Dan_15

Ahhh steamhead. I may have mistakenly given the impression that I have a steam system; in reality I have a Buderus G215 oil boiler connected to a hyrdonic system that was converted from steam. All the rads were replaced with convectors and the pipes in the immediate vincinity of the rads had to be resized, but the mains in the basement are still big old steam pipes.