setting aquastat differential

R. Kalia

I have a very old (27-30 yrs) Weil-McLain with no documentation. There is a dial inside to set the water temperature. Inspired by things I've read, I want to increase the temperature difference between the on and off settings, in order to see if this will make a difference to gas use by increasing cycle times. (The furnace is very oversized, so letting the water cool a bit more won't affect its ability to heat the house on very cold days.)

Now you haven't seen this particular aquastat so maybe this is not a reasonable question...can anyone suggest where I might look to try to find a way to adjust the differential?

I am afraid I'll learn here that it's probably fixed. if so, what is it likely to be fixed at? Or to ask it another way, what's a typical differential used in boilers? I don't have a thermometer with probe.

Many thanks,

Earthfire

30 yr old control

its working , don't mess with it. Look at it say "nice control", and enjoy the feeling in your wallet that says you haven't had to replace it

steve_38

oh yeah

I would definitley take earthfires advice
don't tuch! nicely said earthfire!

Boilerpro_3

It's not the 30 year old controls I worry about

They seem to just keeep going, it's the newer aquastats that seem to be failing. Just replaced a 3 year old honeywell on a friends boiler. Got a Penn- Johnson a couple years ago that was 70F out of calibration right out of the box. Productivity....Ha with no quality control!

Boilerpro

hr

An additional control

could be added and leave that one in place as a high limit control. tekmar makes various boiler controls, Heatimer and a few others.

I tend to trust thermistor based sensors more than the older style capilary styles.

Maybe it't that Pemex, Mexician oil that they are filler with these days, that causes such wide temperature response and/ or inconsistencies!

hot rod

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mellow

burning too much

The reason for doing this adjustment to the control would be to save on gas, right? The control adjustment on a boiler this old could not save that much money. The boiler and piping make the biggest savings. This control change can leave you with a cold house and higher gas bills. Old boilers are not designed the same as new boilers are.