Grassroots HomeHeatingSports

Since you guys know everything...

I have a problem with my home heating system. It is a oil-fired boiler forced hot water system with three zones. On each hot water zone pipe is a Taco. No, not that kind of taco, One of these:

This year, when we fired our boiler for the first time, we noticed that only two of the three zones were coming up to temperature. Of course, the one that heats the biggest room in the house isn't working.

After watching a few Youtube videos, I learned that when the boiler is firing, the #1 and #2 poles on the solenoid part of the valve should be "energized" and show 24 volts. The one going to the room with no heat has 24 volts ALL THE TIME. It's also extremely hot to the touch.

So, anyone know what I should do to fix this?

Thanks in advance!

That's just a zone valve and it sounds like it's stuck. Fixing it might mean replacing it. Do you just have one circulator pump for all three zones?

In reply to Woody:

Yeah, looks like one pump for all three. I think the valve itself is fine. I can manually open it (the lever on it moves), but it won't call for heat.

With power going to it all the time, it sounds as if it's burnt out. It could be hot from the current going to it, of from the hot water that is on the furnace side of the valve.

Do you have a three zone switching relay that sends juice to the zone valve?

When you need heat, your thermostat closes a switch which allows 24 volts to the actuator coil. That opens the valve. It's like an electrical relay for a radiator fan, but instead of energizing a fan, it opens a valve.

I'm surprised that the valve isn't a 'fail open' valve. I guess that might complicate the wiring for a home system... I don't know.

https://www.taco-hvac.com/uploads/FileLibrary/100-3.2a.pdf

I would probably tie the plunger down so that the valve says open until you can replace it. Unless you notice something weird happening, I can't think of it hurting anything. I believe there is an HVAC tech or two on here, so if they contradict me, listen to them.

I would remove the power head from one of the good valves and try it on the non functional one to see if it works.

If it works then put the power head back where it was and replace the bad power head. Based on the pdf that was linked, you should be able to do that without getting wet.

In the interim, you can manually open the valve to get heat to that room. The only thing is that anytime there is a demand for heat from any zone that zone will also get heat so it may become too warm. But you can always close the valve is that happens.

Also, turn down the thermostat below the room temp for that room to see if the relay will turn off the 24v.

That will rule out a bad zone control relay.

Check the dead zone for an air bleed. It'll look just like the schrader valve it is. Push it and see if air hisses out. If it does, hold it down until water comes out.

If there is air in a zone circuit it generally won't circulate. I suspect that may well be your problem.

RossD wrote: I'm surprised that the valve isn't a 'fail open' valve. I guess that might complicate the wiring for a home system... I don't know.

It's probably just "fail last position"?

Ok, so I tested the bad head while the thermostat is switched off. Voltage drops to zero. So, either the valve head is not calling for heat to the boiler, or the valve is stuck shut. There is no air bleed that I can find anywhere.

I went out and bought a new head to try swapping in. Hopefully that works. From what I've read elsewhere, these things go all the time. If it's the valve itself, it will have to be left to the pros.

UPDATE:FIXED IT!!!!!

It was the solenoid head. I just tossed on the new one and it works now. Thanks guys!!!

For future reference, call me, and I will help you out. Between myself, and TR8todd (he's a plumber,I'm an electrician) we can get it going.

Glad you solved it I have had to replace these several times over the years. For the record the big box stores carry these as they always seem to fail at weird hours.

Bump to this old thread... because I had some issues with my heat again.

Since I last posted on this back in 2014, I also had the control box for the igniter/gun/whateveryoucallit fail. Repair guy came out and replaced it with a fancy new one. It's the thing on the right:


Old one just kept tripping the red FAIL button and wouldn't keep the boiler running. The new one actually lights up the FAIL button bright red when it trips for extra FAIL! It's been fine for a while, although the zones seemed to be lazy last winter sometimes. Flipping the shutoff switch usually fixed that.

That brings me to last weekend. I wake up, and the house is cold and the boiler is not firing. I went down the basement, and the FAIL light is not on. Weird. So, I tap the unit with my foot, flick the power shutoff switch a few times, and BAM, lights on the unit flash and the heat comes on. Extra weird. I figured it was a loose connection somewhere, and it was working, so I went on with my day.

Wednesday rolls around, and I wake up and the house is cold. Again. This time, we call in a repair guy, who determines that it's likely the aquastat.

It was nasty and starting to corrode, and maybe it's not consistently getting power to the module. It was also original, from 1992. So, it was replaced with a shiny new one that has a digital temp readout. If it's getting power, that temp readout is lit up. Cool. 

I get home from work yesterday and guess what? THE HOUSE IS COLD. AGAIN.

This time, I go down and look at the whole setup again. Guy told me that the only thing that would make it not fire at this point is a bad module, and since it was already replaced recently, it's not likely that. So, I look at it, and I tap it lightly, and see a spark.

Huh?

The spark came from the jumper wire on the front of the controller. Look at this:

Sorry for the potato pic, but you can see that the left side screw is higher than the right. When I tapped the unit, it sparked between the gap and re-established the connection, causing it to fire up again. The doofus that installed this thing didn't tighten it down! This probably led to the inconsistent heating issues I had last winter as well. I mean, that HAS to be the culprit, right?
 

I was gonna suggest that you change the whole enchilada.

I'll just show myself out... 

In reply to 1988RedT2 :

That has crossed my mind, trust me. That's also very expensive.

Just sounds like a shorted coil on the valve.  That would cause the hot Taco and explain why it isn't opening.

If it's hot all the time, you have a faulty relay that is stuck closed and sending juice all the time (which could explain why the solenoid fried.)

There isn't anything fancy about the valve.  You don't have to replace it with a Taco.  You can replace it with any 24v valve of the same size as long as it is rated for heat and liquids.  Amazon has a few thousand to choose from in the $20 range.  I picked up one (120v) for $18 to use for a theater effect.  It is rated for hot liquid and most of the reviews were from microbreweries who needed them for automation of fermentation tanks.

In reply to 1988RedT2 :

I got it, well done.