i have a weil mclain boiler with a taco sr503 switching relay.zone 1 is for domestic hot water and zones 2 and 3 are for heat.zone 1 is constantly calling for hot water and the two heating zone wont circulate heat.if i disconnect the aquastat on the hot water tank the heat works fine but i dont have hot water.is the problem a bad aquastat?
heat problems
- Thread starter Stevet
- Start date
Tom Sawyer
In the Trades
Sounds like you need to purge the indirect zone or perhaps the circulator has failed on that zone. Once the indirect is hot your other problems will go away. If you need heat tonight, take the cover off the SR502 and look for a dip switch that says priority. Turn it off.
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Jadnashua
Retired Defense Industry Engineer xxx
Yes...the reason the WH is a priority zone is to maximize the unit's ability to make hot water...i.e., hopefully, don't run out of hot while showering. As you saw, if the priority zone is calling for heat, it prevents the others from getting any until that zone is satisfied.
First, check that the thermocouple going to the indirect hasn't become dislodged from its well in the tank...if it has, it won't be sensing the actual tank temperature. Switching off priority will allow any zone to get heat, any time.
First, check that the thermocouple going to the indirect hasn't become dislodged from its well in the tank...if it has, it won't be sensing the actual tank temperature. Switching off priority will allow any zone to get heat, any time.
Tom Sawyer
In the Trades
If the tank was not sensing temp the domestic hot water would be hotter than hell. I', betting on air in the loop.
Tom Sawyer
In the Trades
Yes, you can leave the priority off and I doubt the aquastat is bad. If it was the circulator wouldn't be running.
Jadnashua
Retired Defense Industry Engineer xxx
If they have a tempering valve, as required by code (at least where I live), then they may never know the tank was excessively hot as it couldn't get hotter than the supply temps.
Air, or a bad circulator (but it that one runs all zones, and the other stuff works, it must be good) is a likely problem. If you have a multimeter (and know how to use it!), and the specs on the aquastat, it's fairly easy to test it. It varies resistance with temperature.
Tom Sawyer
In the Trades
If your domestic hot water is hot then your controller or thermostat in the tank is bad
If your domestic hot water is cold then you have air in that loop.
If your domestic hot water is cold then you have air in that loop.
Tom Sawyer
In the Trades
Ok then either the tank aquastat is bad or the wiring is wrong or the relay is bad. Try disconnecting one of the thermostat wires on zone one, the low voltage side which is the top of the control. If the relay opens then you have either a wiring issue or the aquastat is bad. If you pull the wire and the relay stays pulled in, you have a bad relay or possibly a bad SR502 but not too likely
Jadnashua
Retired Defense Industry Engineer xxx
Did you make sure that the sensor (the aquastat) is fully inserted into the well in the side of the tank like I asked earlier? If it isn't fully seated, it won't be sensing the actual water temperature and keep calling for heat. One time on mine, when doing something, the wire got caught and partially pulled the thing out...not enough to drop out, but enough to affect its ability to do its job. All that was required was to push it back in where it should have been.
Also, just for the reason you've seen, it is a very good safety move to have a tempering valve installed to limit the outlet temperature of the WH...having it at say 160-180 or potentially more, is dangerous. Most domestic boilers don't run at boiling or above, but if yours did, once it had the pressure released, it would flash to steam...very dangerous. A tempering valve would mix cold into the outlet to keep it within a safe range.
Also, just for the reason you've seen, it is a very good safety move to have a tempering valve installed to limit the outlet temperature of the WH...having it at say 160-180 or potentially more, is dangerous. Most domestic boilers don't run at boiling or above, but if yours did, once it had the pressure released, it would flash to steam...very dangerous. A tempering valve would mix cold into the outlet to keep it within a safe range.
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Tom Sawyer
In the Trades
What make tank do you have?
If it's an Amtrol boiler Mate then the temperature sensor is mounted up from the bottom of the tank and it in turn runs to the control board on the boiler mate which needs 120V to feed the control and then the two blue (or yellow) wires pull in the SR502 relay. You may very well have a bad controller on the boiler mate, it happens.
If you have a Super-Stor or similar type indirect the aquastat will be mounted on the outside of the unit either in a well installed on the tank or on a fitting near the top of the tank. Either way that aquastat has a capillary tube that must be fully inserted into the aquastat well and if it was working ok before, the chances are pretty good that it is where it should be so, disconnect either wire from one of the terminals on the aquastat and see of the relay opens. If so.....bad aquastat.
If it's an Amtrol boiler Mate then the temperature sensor is mounted up from the bottom of the tank and it in turn runs to the control board on the boiler mate which needs 120V to feed the control and then the two blue (or yellow) wires pull in the SR502 relay. You may very well have a bad controller on the boiler mate, it happens.
If you have a Super-Stor or similar type indirect the aquastat will be mounted on the outside of the unit either in a well installed on the tank or on a fitting near the top of the tank. Either way that aquastat has a capillary tube that must be fully inserted into the aquastat well and if it was working ok before, the chances are pretty good that it is where it should be so, disconnect either wire from one of the terminals on the aquastat and see of the relay opens. If so.....bad aquastat.
the tank i have is a Super-Stor.the tube seems to be fully inserted in the well.i took one wire off the aquastat and the relay does open so it seems the aquastat is bad,thank you.the aquastat is a Honeywell 4080b 1352 which is dsicontinued so i need to find a suitable replacement.Thanx everyone for the advice.
Tom Sawyer
In the Trades
A honeywell L6006 will work
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