Boilers

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Dexie123

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Ok I'm an electrician with limited (no pun intended) boiler experience. Virtually none really.

I don't know the codes but know how to do basic low voltage wiring.

SO here's what I need to do. I have an Aquastat that is wired to a low water cutoff. (See Aquastat photo).


There is a white 4 wire from that Aquastat that goes to the low water cutoff (See Low water cutoff photo and Low water cutoff inside cover photo).

Ok so the issue is this. This boiler has also now two zone valves installed to be controlled by two thermostats. One's existing and the other is new. They are both just two wire thermostats. The zone valves are these valves (See zone valve photo). The zone valves have 2 red wires and two black wires. I'm assuming one set is 24volts power and the other is contacts for the t stat.

I'm going to have to rewire the entire boiler I believe. Any advice would be appreciated
 
The low water cut off needs to go to the boiler. Where to hook it up depends on the boiler.

For the zone valves- one set of wires should be an end switch the other to a solenoid that gets power from the t-stats.

T-stats usually get power from a separate 24V transformer. The end switches parallel to the t, t on the boiler unless you are using a Taco or Tecmar control box.
 
Any of the low water cutoffs I have ever done are line voltage and are wired to kill power to the boiler, usually in series with the service switch. I believe this is code.

As for the aquastat, what does it do? Is it a high temp limit, low limit, maintain temperature for a boilermate or what? You have to know the purpose of these controls in order to wire them and aquastats can be used for lots of things.

I also wouldn't worry about how it was wired. Most plumbers don't know boiler controls and wiring either so it's entirely possible that what is there is wrong.

-Hal
 
Thanks guys. The low level cutoff is low voltage for sure. If it's easier maybe I could email one of you guys the photo's and you can post them for me?
 
Boiler

Boiler

Do you have the model number for the low water cutoff and aquastat?

I know for sure the low water cutoff requires a 24volt supply.

Where to locate the contacts from the low water cutoff will depend on the type of aquastat.


Joe Villani
 
Thanks Joe.

I have the Aquastat relay L8148e and the low level cutoff is a 400 series. If possible I could email you the photo's and maybe you can post them? If you know how that is.
 
Boilers

Dexie123

I am assuming the 400 series low voltage cutoff is safgard series

From the L818e get 24 volts from Z and TV. This will go to 1 and 2 on the safgard.

Remove factory jumper from the safegard.

Remove wire from the R terminal on the high limit splice low voltage wire to low voltage wire to P2 in safegard.

R terminal on the high limit will go to P1 in safegard.

What you have done is break the control to the burner. If the low water limit is satisfied power will pass though the normally closed contact in the safegard to the burner causing it to fire.

It appears this is a cold start boiler, only firing when a thermostat calls? If so you can do it with 3 wires.

Remove the jumper between z and W. Make sure you z terminal goes to 1. TV goes to 2. (24volts at the safgard)

Jumper in the safgard remains in place. Connect W from the aquastat to P2. Relay 1k will not make unless the safgard is satisfied.

You will need to install a seperate 24 volt transformer for your zone valves.

If you need assistance wiring the zone valves just ask.

Joe Villani
 
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