HELP with thermostat problem

John Starcher_4

....sub-base for the thermostat? I have seen where a problem can develop in the circuitry of the sub-base, causing an excessive amp draw, which produces heat.

You could actually watch the mercury bulb tip after the sub-base warmed up.

What is the actual amp draw of the control circuit??

Starch

Brian in Indy

Friends - I simply can not get our WM LGB-6 boiler to run with a new thermostat - have tried two Honeywell stats to no avail. Have checked wiring for opens and shorts. Boiler runs great. Old thermostat was bronze colored round H/W, it worked well, pipefitter threw it away before I could get to it. Here's the deal: turn thermostat to above room temperature, boiler comes on, minute or two later boiler shuts off - go to thermostat, you can turn it up a little bit, mercury switch will make, boiler will run for a little bit, goes off, the cycle continues. If the thermostat sits for awhile (not turning temp up) the boiler will come back on and repeat the cycle. I have tried anticipator settings of 0.6 (amperage on gas valve) and 1.2 (setting suggested in instruction manual).

My gut feel is too much current going through the thermostat, heats something up, and the switch opens?

HELP

THANKS

Brian

Brian in Indy

yes, this is what I'm seeing - I'll measure current draw tonight -

THANKS

Dale

What is new?

What stat do you have now, not too much with mercury anymore. Did you take the "new" stat off the wall and use a ac ammeter to see what the amp draw really is? Is the new stat level? Must be level if it's mercury. Is there a hole in the wall behind the new stat or some heat source below it? What is the voltage of the new boiler? Over 27v closed circuit, watts = v x a althouth this is usually a cooling problem. I would start letting an ammeter be my stat for a half hour or so to see if the boiler keeps running. Set the anticipator to actual amps for a start and check the stat with a good digital thermometer to see where it's opening.

Brian in Indy

OK - I'm seeing 1.8A when the gas train is on, checking from the transformer through ammeter to boiler control. Sounds high - thoughts? Do I need a special thermostat? The Honeywell Round has a max anticipator setting of 1.2.

THANKS

Brian

Unknown

1.8 is excessive

replace the primary control(that is the control the thermostat is directly bringing on, gas valve, relay, zone valve etc) you are pulling to much amperage.

What is the primary control?

It sounds like with all that amperage that the anticipator is getting real hot and shutting down the thermostat. The primary control what ever it is other than maybe a Taco Zone valve should not be pulling more than 1.0 amps.

Is the transformer a NEMA (National Electrical Manufacturers Assoc)rated class II standard DC 20-92 if not then replace it with one that is. Transformer voltage should be between 26.5 volts to a minimum of 21 volts.

Brian in Indy

Thanks for the quick reply. The gas train is made up of:

(1) Honeywell V88A1618A (nameplate 0.62A)
(2) the above feeds into a small electromagnetic valve (pilot/ignitor?) Honeywell V8046C 1014 (nameplate 0.586A)
(3) number (1) is piped into a big Honeywell valve, no nameplate, this is the main burner valve

The power supply looks like a Honeywell, no nameplate, open circuit voltage is 24VAC.

There are two solid state ignitors, Honeywell S8610U.

THANKS

Brian

Brian in Indy

Thanks for the quick reply. The gas train is made up of:

(1) Honeywell V88A1618A (nameplate 0.62A)
(2) the above feeds into a small electromagnetic valve (pilot/ignitor?) Honeywell V8046C 1014 (nameplate 0.586A)
(3) number (1) is piped into a big Honeywell valve, no nameplate, this is the main burner valve

The power supply looks like a Honeywell, no nameplate, open circuit voltage is 27VAC.

There are two solid state ignitors, Honeywell S8610U.

THANKS

Brian

Boilerpro_3

Those combined controls draw alot of power

and a 75 VA transformer is required, so the amp draw probably is OK. It sounds like you need an intermediate relay to switch the burner primary controls. A simple fan relay center mounted on a 4 x4 box should do the job. However, Timmie is the man when it comes to gas trains.

Boilerpro

Brian in Indy

YES! - The last guy that was here (knucklehead?) unwired the relay hanging off the side of the 4x4 box holding the xformer "this must be for some a/c or something they were going to use" ... I'm a EE, a wiring diagram would explain everything - it's all starting to make sense.

THANKS

Brian

Unknown

Sounds like someone

unwired the relay which would have isolated you from the high amperage draw of those controls. Do you have the installation manual? If so there is probably a wiring diagram. If not try Weil McLain web site www.weil-mclain.com