Aquastat L8148J

cbassett

Hi everyone,
I just installed a new AquatatL8418J on my boiler (along with a new expansion tank, pressure relieve valve nut and automatic pressure vent) and I can't get heat. The boiler turns on, the water heats up but I can't get it to send out the water when the thermostats call for it. I have 2 zones with separate thermostats and it isn't working for either so I am fairly sure it is not the thermostats or the zone valves causing the problem. I labeled all my wires and rewired it based on the labels but I am wondering if I messed up. I am thinking it is the T and TV connections that would be causing this particular issue but I don't know enough about it to be sure. For fun both wires are red so its difficult to tell which is which and they both lead out to red wires on the zone valve motor boxes.


Side note, the replacement was technically L8148J1009 and my original one did not have 1009 on the model number but they looked exactly alike so I was guessing they updated the model number in the decades since the original was installed,

SuperTech

Sounds like the circulator might not be working?

cbassett

@SuperTech
I thought about that, anything is possible since it has been off for the summer but the relay doesn't engage when the thermostat is turned on, and if I manually press the relay the pump seems to come on, would that happen if the circulator is the problem? I have zero background in this stuff except that I have been learning as things break on this heater for a few year now.

mikeapolis

2 Honeywell zone valves? What are those wired to?

cbassett

Not sure it’s the same model but they look like this one
@mikeapolis Yes 2 Honeywell zone valves. Each has one red wire that is spiced to the other valve and the T connection and another red wire that is spliced to the other valve and the TV connection and they each have 2 yellow wires (I didn't touch the yellows at all) that connect down to something else I haven't traced but I would assume they go to the wall thermostats eventually.

mikeapolis

Batteries good in the T-stats?

cbassett

@mikeapolis I didn't check. But they are both the old round mercury thermostats, do those have batteries? And the back one makes an audible click when it engages that I can definitely hear.

mikeapolis

I was wondering if they were twined to the aquastat or wired to a Taco valve control. Can you manually open each zone valve?
The red wires are the end switch wires and the 2 yellow wires(T-stat) are for the zone valve motor.

mikeapolis

No batteries in those t-stats. Just mercury

cbassett

@mikeapolis I can manually open both valves with a little lever on the back. They appear to be twined directly to the Aquastat, I'm not sure what a taco valve control is but I don't think I have one. I'm worried that I switched the T and TV connections when I rewired it, even though I am pretty certain I put them back the same based on pictures I took of the old and new one. Could that cause the issue? And if I switch them and it wasn't wrong could I accidentally break/ short something even worse?
Thanks for the help!

SuperTech

Its always possible that two Honeywell zone valves are malfunctioning at the same time, but something has to be telling the boiler to turn on and fire the burners. 
The red wires are a normally open switch, this switch tells the aquastat to turn on the burners and circulator by the relay engaging. The yellow wires go to the thermostat for their zone. 

What did it do before you replaced the aquastat? Do you have a flue damper?

cbassett

@mikeapolis No flue dampener that I know of.
The reason I replaced the aquastat was that the relay switch had been going out on the old one and wouldn't engage half the time. I did replace the zone valves in the last couple of years and when those went out they buzzed, which they aren't doing now.

STEVEusaPA

It's simply wired wrong.

cbassett

@STEVEusaPA That's what I was worried about, but I was having trouble understanding the wiring diagram. Can you help tell me what I wired wrong?

cbassett

@SuperTech No flue dampener that I know of.
The reason I replaced the aquastat was that the relay switch had been going out on the old one and wouldn't engage half the time. I did replace the zone valves in the last couple of years and when those went out they buzzed, which they aren't doing now.

STEVEusaPA

cbassett said:

@STEVEusaPA That's what I was worried about, but I was having trouble understanding the wiring diagram. Can you help tell me what I wired wrong?

I don't know what wires go where. Maybe you can sketch out what you have. I also don't know enough about your system to see if you need the jumper.
I also don't see any wires on W.
What kind of gas valve?
Is the system properly grounded?

Are you sure these wires are good? looks like there was a short on the last one.

cbassett

@STEVEusaPA W wasn't wired on the old one either, it just had a jumper connection to Z, which was then jumped to TP. The two red wires have been discolored like that since I moved in so I don't think the wires shorted Green wire on the bottom is grounded to a copper screw.

cbassett

Here is the old wiring for comparison in a pic I took a couple years ago.


vs new one

HVACNUT

Where are the yellows for the zone valves going? It's as if there's an external transformer powering the zone valves and the reds close TT on the aquastat. If that's the case, you spent an awful lot for an aquastat you don't need. You could have gotten an L8148A or a Hydrostat 3250 Plus.
If the zone valves aren't opening with the thermostats raised, then check for 24v on the external transformer. 

SuperTech

On the old one you have a red wire to W, on the new its going to T and T. Have you tried wiring it like the original control. 
Those are some strange,  burnt looking red wires you are using instead of regular 18 gauge thermostat wire to your zone valve end switches. 

cbassett

The angle of the pic doesn’t show it great but it connects to T, W only had the jumper connected.  Not sure why they used those wires but they are the sane gauge as the ones coming off the zone valves that they splice to.

cbassett

@HVACNUT the yellow wires run into this box I don’t know about. 

HVACNUT

That "box" is a transformer. The Blue and Yellow wires are 24v. One wire should go a yellow on each zone valve, the other wire should splice to two more wires that go to the thermostats. A wire back from each thermostat to its remaining corresponding yellow at the zones valves. 
Do you have an electrical meter to check if the transformer is good? If that transformer is shot, you can use the L8148J alone but things will need to rewired like the diagram @STEVEusaPA posted.

cbassett

@HVACNUT @SuperTech @STEVEusaPA Update- got a multimeter, tested all the connections, turns out I closed the return valve while I was fixing a leak that sprung up in the process of replacing part of the pressure valve and that was the whole problem. Thanks so much for your all your help!!!

HVACNUT

I should've made that left turn at Albuquerque. 
Happens to the best of us.