Amtrol BOILER MATE WH-7P thermostat or Aquastat problem?

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Old 06-05-15, 09:15 AM
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Amtrol BOILER MATE WH-7P thermostat or Aquastat problem?

I have the AMTROL WH-7P BOILER MATE Hot Water Maker which I installed in 1993/94. It has the manual/rotary thermostat control. My system consists of a Well-McClain P-WGO-4 series 3 boiler; Honeywell L8148A Aquastat; Taco SR-504 (four zone) switching relay; a Honeywell R8184G 4009 Intermittent Ignition Oil Primary Switch; and four Taco 007 circulators (3 for baseboard heat; one for domestic water). I also have a Laing circulator pump for a domestic hot water loop which runs about 45 feet each way.

Yesterday, I noticed that the temperature of the boiler was well below 100 degrees. I normally have the BOILER MATE set to 130 degrees. I initially hit the reset button on the ignition. This did nothing. I raised the temperature up on one of the heat thermostats and the boiler turned on. I backed it off and the boiler shut down. The domestic hot water is set to get priority in the switching relay. I raised the thermostat on the BOILER MATE to about 135 and the boiler kicked on.

If the BOILERMATE is below that temperature, the boiler is not cycling on. I originally was thinking that the BOILERMATE thermostat was bad but now am leaning towards it being the Aquastat.

A side note….I have had an ongoing intermittent issue with the boiler cycling on for about 20 seconds and then off only when the heat is running. This happens when the boiler is already at or close to the high temperature (180 degrees).

I have a service contract with a local Oil company. They have never been able to figure that out. They did replace the Aquastat (with a used one I suspect) but the problem continued. As I stated, it is intermittent so one may have to sit for hours to actually witness the event.
I am hesitating to call for service since the last Aquastat cost me almost $300 since the BOILERMATE (domestic water) is not covered.

Thanks in advance for any suggestions.
 
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Old 06-05-15, 11:10 AM
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temperature of the boiler was well below 100 degrees
You did mean to say BOILER and not BOILERMATE, correct?

I raised the thermostat on the BOILERMATE to about 135 and the boiler kicked on.
I'm not seeing a problem here.

If the water heater thermostat was satisfied, the water in the heater was at 130, then why would you want the boiler to be cycling?

If the BOILERMATE is below that temperature, the boiler is not cycling on
I'm confused by this statement.

Are you saying that even when you run hot water and the boilermate cools off to below the setpoint of it's aquastat, that the boiler will not fire?
 
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Old 06-05-15, 04:25 PM
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Hi

Thanks for responding..

Yes...I meant to say BOILER..

I believe the aquastat normally would cycle the boiler on when temperature falls below 140~ and off when it reaches 180~. That is basically how the system was running until yesterday when I noticed that the BOILER temperature was below 100. The BOILERMATE thermostat was set to 130~ therefore the boiler should have cycled on.

Sorry for confusion......Yes, I was saying ..."even when you run hot water and the boilermate cools off to below the setpoint of it's aquastat, that the boiler will not fire?"

Well, after I posted....I turned off the power and cleaned out the aquastat and the thermostat with canned compressed air......and moved turned the thermostat from minimum to maximum several times...and now everything seems to be working! I still think something's going on with the aquastat but am going to leave it alone and just keep an eye on it...

Thanks!
 
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Old 06-06-15, 07:53 AM
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I believe the aquastat normally would cycle the boiler on when temperature falls below 140~ and off when it reaches 180~.
Honeywell L8148A Aquastat
No, that's not so.

The 8148A aquastat is a COLD START aquastat, meaning that in the absence of a heat call, either from a central heating zone, or the water heater, the boiler would not fire, and could cool all the way to room temperature.

In other words, it will only fire when told to. It won't fire up to keep itself warm.

That is basically how the system was running
Not likely.

The BOILERMATE thermostat was set to 130~ therefore the boiler should have cycled on.
No. The Boilermate aquastat is measuring the temperature of the water in the tank, not the boiler. Only when the tank drops below the setpoint (130) will it call the boiler to fire.

The 8148 is what controls only the HIGH LIMIT of the boiler water temperature. There is no LOW LIMIT on the 8148, it's a COLD START aquastat.

moved turned the thermostat from minimum to maximum several times
"Thermostat" means the control on the Boilermate? (it's actually an AQUAstat, measuring the temp of the WATER inside the tank. Thermostats measure AIR temperature)

They do sometimes get 'sticky'. You could be OK for the rest of the tank's lifetime, or it might happen again. Only time will tell.
 
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Old 06-08-15, 10:04 AM
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NJT,

Thanks for the very detailed response!

I understand the system much better now....
 
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