Radiant zone off - floor temp still increasing and well over max temp (Taco Comfort)

jvr

Hello - (I do have a tech coming here next week but we have a unique situation where one company will service our boiler and not the rest of our heating systems. The other company will do the plumbing/heating but not the boiler. And they refuse to talk to each other. So a lot of "it's the boiler" and "it's the circulator" and back and forth. It's a PITA and very frustrating as a customer. I'd like any help we can get so when they come out and try and point the finger at the other company, I'm a bit educated on the issue.)

We have a 3 zone Taco ST503-4 switching relay with Taco VR1816 circulators and a TekMar thermostat. I noticed yesterday that one of the zones (shown as "bedroom" on relay box) was VERY warm (75º) and the floor temp said 88º. These are both well over our set temps and max floor temps as we have hard wood flooring over the cement slab. I immediately shut off the heat in that zone. A few hours later, the floor temp went down to 86 so I thought I was making progress. Closed off doors to that room and this morning the floor temp is back up to 88 and rose to 89. It's still "off" and not calling for heat.

The switching relay is not illuminated for that zone and the circulator is also not illuminated for that zone. The pipes are quite hot for that zone and a IR temp reading of the floor in the "hot bedroom zone" is showing 81-84º (vs our other zone - living room - that is correctly working and showing 71º - and also shown in photos as calling for heat).

I checked the setting on the thermostat and the max floor temp is set to 80º and the room temps are set to 70 and 72 based on time of day/night. It is NOT calling for heat and is still off.

We've checked the fuses in the switching relay and they are fine. Again, that zone is not on according to the relay or circulator.

We did call Taco Comfort and they told us to call a plumber. :-( So no help there.

Important info: hot water supplied by Lochnivar combi boiler, new construction installed in 2017, now on day 4 of a cold snap with temps down to the teens which is unheard of for this area. We DID turn on a zone (upstairs) for the first time in 2 years on Sunday for half the day. Did not notice the other zone (bedroom) getting too warm until Monday afternoon. Turned on the upstairs again last night - could that have something to do with it? It never effected the floor temps in the past that we could remember and we were VERY cautious due to the hardwood flooring.

Jamie Hall

In the photo it looks to me that zones 1 and 2 are both on. In any event, it's not the boiler -- it's something in the control wiring or, possibly, the zone valve sticking.

hot_rod

Three zones with 3 zone pumps?

a pic of the boiler piping might help 

EdTheHeaterMan

Looks like only zone 1 is calling RED. Zone 2 and 3 are off but there is a slight bleed over from zone 1 LED on zone 2 display.

Do you have any manual valves that can be shut off to zone 2 to stop the flow of hot water to that zone?

There may be any number of problems that are not boiler related. The manifold may have valve actuators that are not closing. if there are no Flo-Check valves to keep the heated water from going backwards into the zones that are off, you are probably getting heat from the calling zone backing up thru the zone that is off.

That is a piping design issue. and when someone installs piping wrong, it is tough the get them to understand their mistake. Happens all the time.

jvr

Jamie Hall said:

In the photo it looks to me that zones 1 and 2 are both on. In any event, it's not the boiler -- it's something in the control wiring or, possibly, the zone valve sticking.

We have noted that in the past - it's just a bleed over from the LED light above it being on. It's always been that way, but when actually "on" the LED is very bright and obvious. But thank you for noting it.

jvr

EdTheHeaterMan said:

Looks like only zone 1 is calling RED. Zone 2 and 3 are off but there is a slight bleed over from zone 1 LED on zone 2 display.

Do you have any manual valves that can be shut off to zone 2 to stop the flow of hot water to that zone?

There may be any number of problems that are not boiler related. The manifold may have valve actuators that are not closing. if there are no Flo-Check valves to keep the heated water from going backwards into the zones that are off, you are probably getting heat from the calling zone backing up thru the zone that is off.

That is a piping design issue. and when someone installs piping wrong, it is tough the get them to understand their mistake. Happens all the time.

We shut off the valves on either side of the circulator for the bedroom zone earlier today. (the 2 ball valves on either side) That has successfully lowered the floor/room temp in the bedroom.

Your point on the piping design issue - it's one we thought could be the problem - we just never noticed the floor getting to 90 in the past when we ran the heat in the upstairs room. I will post an update of the whole system in case y'all can find flo-check valves (we can't be aren't 100% sure what we are looking for).

Thanks again.

jvr

Update with full photos and with the problematic zone on and calling for heat (so you can see the LED light status differences) The boiler is to the right mounted around the corner so you only see a side shot.

I'm not seeing any additional valves between the circulators and the line into the house feeding each zone but I'm not certain what i'm looking for as they were all so different when I googled them.

dko

The vr1816s come with flow checks in the box, but doesn't necessarily mean the installer put them in.

Installer also didn't rotate the motor housings, hurts to see.
Also installed a potable water expansion tank, hopefully the charge was reduced to the proper psi.
Above two things don't relate to your issue, but not having any flow checks installed (or stuck) on the pumps can be.

dko

https://youtu.be/s-UyMmnPiiI?feature=shared

To see what the ifc looks like and where it goes.

hot_rod

Nice attention to detail by the installer, insulation, clean wiring, all brass piping on the fill valves. Even a drain on the backflow.

It could be a failed check. Sometimes the checks are in the isolation flange valves.

EdTheHeaterMan

It is difficult to see if there are any flo-check valves with all the pipes covered in insulation. They may be slim and conform to the size of the pipe. The recommended Flo Check valves look like this

There may be other types that can actually fit inside the pump

If you look at this illustration of what your system might look like past the boiler room, you can see the Pink arrows show the path of the heater water flowing through the system. This would be the normal flow. But the water may flow backwards if you do not have check valves. The Green arrows indicate what may happen if there are no check valves.


This is only a guess as to how your system may be connected past the boiler room. If you have additional temperature mixing valves that are not visible in the photo, this reverse flow can have higher temperature water flowing in reverse to the unused zones. Your boiler man may have connected the boiler to the system incorrectly. The system piping may be incorrect. Without seeing all the pipes from the boiler to the floors, it is difficult to know where to point the finger.

What you actually need is someone that will look at the entire system to determine the proper fix.

Joe Mattiello

Suggest you contact Taco tech support at401-942-8000 for help 

jvr

Joe Mattiello said:

Suggest you contact Taco tech support at401-942-8000 for help 

Hi Joe - we did. And were promptly told to call a plumber.

jvr

EdTheHeaterMan said:

What you actually need is someone that will look at the entire system to determine the proper fix.

I just wanted to thank you for taking this time to clearly explain and illustrate everything. And to point out the valves may be inside the circulators. This is what we "thought" could be happening - because it just started and was never an issue since 2017 - and know the flow-check valves aren't necessarily another thing on a pipe somewhere.

When our technician comes out on Monday, we are very happy that we have the knowledge to follow along with what he's saying! Thanks so much!

And to everyone else that commented - thank you for your time. We really appreciate the help and you all sharing your knowledge! (the ice storm caught up with us and we've been without power/cell for the last day and half)

EdTheHeaterMan

That pipe diagram is only a guess. The near boiler piping may not be exactly as I illustrated, In fact it is probably not. If it is "as illustrated" then that can be part of your problem. Which would place it in the boiler guy's area. If you don't have the check valves, that would put it in the system guy's area

Can you show the piping above (if any) and below the boiler and how it gets to the system? Also what is the boiler brand and model number?

jvr

EdTheHeaterMan said:

Can you show the piping above (if any) and below the boiler and how it gets to the system? Also what is the boiler brand and model number?

You are actually correct. The system is a floor below all the heated floors so it goes into the 2nd floor from the photo. And what you see in the photo is the only parts of the pipes exposed in our basement - everything else is buried in insulation. The water comes from the boiler as you note in your image, into the big tank.

The Boiler is a Lochnivar Combo boiler. I'll need to look up the model number.

We have had the problem zone (bedroom) off for the past week and it's has maintained a very warm 71-75º even with the upstairs OFF as well. This is a new behavior for sure so there's a flo check valve gone bad somewhere. If it's in the Taco circulator then I think that's our issue. Now to try and get Taco to send a replacement!

hot_rod

If you don't have checks, or they are sticking, here is what can happen with zone pumps.

The trunk or manifold that the pumps are connected to should be able to move the total flow, lets say 12 gpm in your case with all pumps running.

The flow in the manifold or heater should be 8 gpm at 2 fps. So that pump manifold would like to be 1-1/4" copper..