But why?

[sparky1118]

I haven't been to the job yet. They will be replacing a furnace tomorrow which I will be working. I have never seen so many relays on a heating system. Has anyone seen or know why they would do such a thing?

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[Fred B]

Operating a zonal control system?

 

[Dennis Alwon]

I expect it is zone heating also. Best to keep that together as best you can. Label it well....

 

[sparky1118]

I expect it is zone heating also. Best to keep that together as best you can. Label it well....

I was thinking of replacing this mess with a Taco zone board. Hoping it would still function the same way.

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[sparky1118]

Operating a zonal control system?

Not sure. I haven't gotten my eyes on it yet. The plumber sent me the pictures to warn me. He said he's never seen a system like it before.

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[hbiss]

They will be replacing a furnace tomorrow

Furnace or boiler? This is like saying "plugs" instead of "receptacles". "Furnace" and "boiler" are two completely different things that people don't bother to distinguish.

You need to look at it. I suspect 4 zones with a circulator for each zone. Original installer was probably an electrician who had no idea about hydronic controls. Or he had those on the truck. Or they were cheaper.

If hydronic, you are correct. Replace the mess with a Taco zone controller, you will need a 6 zone. I think they go from 2 to 6.

-Hal

 

[sparky1118]

I was just told there are a total of 8 zone valves. Should be fairly straightforward I just never seen this setup before

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[hbiss]

I was just told there are a total of 8 zone valves. Should be fairly straightforward I just never seen this setup before

8 thermostats, 8 zone valves with 8 end switches wired in parallel to turn on the boiler and circulator, one circulator. Would be nice, right?

How come there are four relays marked 1,2,3 and 5?

Are there heating/cooling thermostats for A/C and heating? Maybe zones 1,2,3 & 5? Maybe the relays are used because the thermostats are powered from the A/C units, and he needed a set of dry contacts to control those four zone valves which are powered from a separate transformer along with the rest of the valves?

-Hal

 

[sparky1118]

They ended up running all the zone valve wires to one j box in the crawl space and having one 18/8 and 18/3 going back to the boiler. I ended up installing two zone boards and running individual wires back to the new boiler. Still no idea what they had going on with all those relays.

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[hbiss]

As long as it works.

-Hal