AquaSmart 7600B lockout freezing my tenants half to death, jury rig fix?

ColdInTheNorth

Hello all! I've been lurking on this site for a bit, I am a HVAC amateur who worked in construction for half a decade a while back (though in masonry). I do some light electrical work and am comfortable with DIY.

My old apartment that I rent out is heated by a gas fired boiler with radiant heat through the baseboards. Unfortunately, it's managed to break on president's day weekend, with dangerously cold temperatures here in Chicago. No professionals I've talked to can get a replacement control unit until Thursday or Friday, which would leave my tenants too cold. I've bought them a couple of space heaters, but that's not a realistic solution for below zero.

The AquaSmart is throwing a self-check lockout when powered on. It had previously done so twice over the last year in the winter. When that happened, resetting it had been enough. Now however, it self-check locks out about 10 seconds after powering on.

Breaking out the manual and my multimeter, B1 to B2 voltage is over spec, which I believe is causing the self check lockouts. It's a single zone, fairly simple, settings are set to the default. There is a damper, but I don't remember it ever being connected, the wiring is not currently connected to the control, and the jumper plug is in place.

May I have the community's feedback on a few things?

1. Should I order a 7600B, or a 7610B to replace? Not sure why they came out with a different model number.
2. Any longshot troubleshooting I can try on this control to make it work, even for a few hours?
   1. I know ZR is also 24 VAC out, but not sure how I would configure the control.
3. How feasible is my plan to jury rig to keep the house warm for a couple of days:
   1. Buy a 24V transformer from Home Depot/Lowes
   2. Wire the transformer to power and reconnect B1 and B2 to the transformer.
   3. Connect C1 and C2 directly to L1 and L2 to keep the circulator running.

I can periodically reset the Aquasmart and get the temperature reading to make sure it doesn't get too hot.

Big Ed_4

The problem seems to be in the burner circuit , do you have a meter ?

ColdInTheNorth

I have a multimeter, what should I be looking for/measuring?

EdTheHeaterMan

3. How feasible is my plan to jury rig to keep the house warm for a couple of days:

a. Buy a 24V transformer from Home Depot/Lowes

b. Wire the transformer to power and reconnect B1 and B2 to the transformer.

c. Connect C1 and C2 directly to L1 and L2 to keep the circulator running.

DON'T DO THIS:

b. Wire the transformer to power and reconnect B1 and B2 to the transformer.

You would be bypassing a very important safety feature. The high limit. 

See if Home Depot or Lowes has a strap on aquastat to be the high limit and set it to 170°F and place it on the supply pipe as close to the boiler outlet as you can. Then wire it from the 24 VAC transformer R to the thermostat R from the thermostat W to the wire that is on the aquastat R. From the Aquastat B connect the wire that is on the Aquasmart B1 terminal by removing the wire . Take the wire from the B2 Terminal off the Aquasmart and put it on the C from the transformer

follow this diagram:

Remove wire from B1 and B2 for this temporary fix and add a jumper wire from L1 to C1 to make circulator run constantly during the temporary fix.

YOU MUST HAVE A HIGH LIMIT like this one L6006C strap on Aquastat

ColdInTheNorth

(Edited, Ed's answer made redundant)

EdTheHeaterMan

The Aquasmart will know the limit temperature but that does not work. The temperature gauge will tell you what the temperature is and I would stop the burner at 180°.

But you want to eliminate the human error factor, like if you get distracted by a phone call of something else. The Strap On Aquastat is the best idea. See if HD has it in stock https://www.homedepot.com/p/resideo-Aqua-Stat-L6006C1018/202656692

ColdInTheNorth

Thanks Ed,

So the supply pipe is a decent enough proxy for the water temp in the boiler to use the strap on Aquastat, given the circulator will be constant on?

Steamhead

Get the 7610B. Some of the 7600s had that problem, but the 7610s seem OK. And use a new sensor as well.

EdTheHeaterMan

YES. but set it at 170° for a safe margin. You may not get all the way to 68° inside some apartments but you will get close