Lifebreath hvac possible relay failure

bhilton

Hello, I had a power surge take out my thermostat yesterday, as well as the 2A fuse in my lifebreath furnace board.

After installing a new tstat and replacing the fuse, my cold air and compressor work great.

But when the tstat calls for heat I think I have issues.

The tstat is wired directly to the lifebreath hvac, C,Y,G,R,W.

Three things are supposed to happen  when the tstat calls for heat:
1. The lifebreaths blower fan comes on (and it does)
2. The groundfos pump on the lifebreath comes on (and it does)
3. A dry contact relay on the lifebreath circuit board called “contact 1” goes from open to closed (see manual linked below, on page 20), this relay is wired to the R and W for zone1 on my Taco sr502 relay which fires the boiler via end switch and also sends the zone1 power 120v to the actuator (goes from closed to open) on the hydronic loop allowing the lifebreath groundfos pump to circ heat from the boiler through the lifebreath. 

That 3rd bit is no longer happening.

I don’t think the “contact 1” relay is switching from normally open to closed.

The zone1 light on the sr502 is not lighting up and therefore the zone1 relay is not closing to allow power to the actuator nor is the end switch turning on the boiler.

I believe I ruled out the possibility of the sr502 being bad because if i jump the r and w on the zone 1 terminals manually, the boiler fires and the actuator opens.

Any advice on what I can do? What further testing can be done? Any workarounds like utilizing W2 on the tstat to call zone1 on the taco? Maybe i can buy a $10 separate relay switch off amazon and work around it?

or am I at the mercy of a new control board in the lifebreath?

https://www.lifebreath.com/wp-content/uploads/2022/04/69-AH_Manual_EN.pdf?x17307

Thanks so much!


Regards,
Bill

109A_5

Hello @bhilton,
Any other fuses blown ? I would be surprised if whatever took out the fuse damaged a relay, but not impossible. Are the relays K8 and K7 etc. in sockets ? If so you could swap them as a test. You would think the Relay numbers would correlate with the Contact numbers, oh well, hopefully the relays are actually next to the wiring connections.
Relays of the type used here are usually inexpensive at www.digikey.com or www.mouser.com and other vendors. The part number is often printed on the relay. Relays that are soldered to the circuit board can be replaced, just more tools and skills are needed.

I'm assuming there is 24 VAC across N.O. to COM relay connections of Contact 1 when the system is idle. However, be careful since it could be 120 VAC, depending on your system.

Does a jumper here (Red annotation) fire the boiler ?

bhilton

Thanks for a quick reply!

I didn’t see any other fuses on the lifebreath board. 

Yes if I jump the two contacts on where R and W connect to the relay, it turns on zone1 on the taco.

Are these soldered or removable?

PC7060

Most like soldered. 

Do you have a ODR on the system?. It’s common for the system to shutdown/not fire on high outside temperatures. 

109A_5

Hello @bhilton,
As best I can tell from that picture (camera shake and the angle of view) the relays are not in sockets. The sockets would be a separate structure between the relay and the circuit board. If you really think the relay is bad they are not expensive, https://www.mouser.com/ProductDetail/Song-Chuan/833H-1C-C-12VDC?qs=X4N6sOTYzkgmOWwYJwJPXg== (Mouser Part #: 893-833H-1C-C-12VDC), however you would have to find someone with the tools and skills to change it, only a few minutes work to change. I'm assuming the relays go to the connections the arrows point to, but they may not, you don't want to change the wrong relay.

If you have a multi-meter I would verify the 12 and 24 VAC is coming out of the transformer (Red annotation).

@PC7060 there is a thermistor but I don't think it is for Outdoor reset (Orange annotation).

109A_5

Hello @bhilton,
If the electronics controlling the relay for Contact 1 is damaged, you may be able to do something like this. Although there may be unforeseen side-affects or unintended results.

bhilton

@109A_5 thanks, I was hoping as a last resort I could do that! What relay would you buy for that external relay setup?

Also, anyone know how I can test the relay itself?

Additionally, I believe I am capable of doing a desolder and solder of a new one. If the contacts are not too tiny… lol

109A_5

Hello @bhilton,
Some methods I would do to test the relay is;
Ohmmeter test the relay coil and compare the readings to the other like relays.
The relay could be removed from the circuit board and tested with a power supply, a meter, and a lamp or other 12 VDC load.

Another method to test the relay and its control circuit is.

Take a picture or document the wiring with a drawing.
Turn all the power off !!!
Remove the board enough to access the relay solder connections, disconnect wires as needed.
Verify which relay is associated with Contact 1.
Solder two wires to the coil side of that relay.
Safely support or re-install the board, reconnect the all disconnected wires, connect a DC Voltmeter to the added wires.
Be very mindful that nothing touches anything is should not be touching.
Power everything up.
Make a call for heat.
The board should apply about 12 VDC to the coil of the relay, the relay contacts should close, the boiler should fire.

If the 12 VDC to the coil is present and the boiler does not fire more troubleshooting is needed to verify the relay is the actual defect. Like is the relay physically activating the contacts and they are not electrically closing, or the relay coil is open, in which case I would think there would always be about 24 VAC across the N.O. and Com contacts.

If the 12 VDC is missing across the relay coil maybe some other board input is absent or active so the board logically will not initiate a call for heat or the electronics that control the relay has been damaged so the board no longer has control over that relay. Some of this should be verified first before any of the above is done. It is a Treasure Hunt.

Troubleshooting methods need to be dynamic as information is learned, this provides direction to the actual defect.

This type of work is not for everyone, stay safe, don't cause any more damage, know your capabilities and limitations.

BTW with the external bypass relay scenario, functionality like 'Reheat' (if it existed in the first place) may be lost if it otherwise solves the problem.