Overheating radiant system

Jsipzner

Hi all,  I have a multi zone radiant heat system (pic below). Recently,  been having an issue where 2 of my zones have been getting very hot despite no heat being called for by the respective thermostat. Have had this system for five years and have never had an issue.  As you can see below,  the only way i can keep my bedroom from getting to near 80 degrees is to shut the valve off which it's obviously not an ideal situation. Does anyone know why hot water would suddenly start flowing through the pump despite the pump never getting activated (which i confirmed by completely turning off the thermostat and i still feel the pipe getting warm above the pump). Thanks!

EzzyT

Ghost flow is what is occurring, could be a bad check valve thats inside of the circulating pumps  or possibly another pump by the boiler is overcoming the check valves inside of the zone pumps.

Jsipzner

Thanks.  That's helpful and makes sense.  On your second point, that could be right.  The one change between this year and last year was this pump (pic below) which pumps down into the boiler was replaced  and I imagine running more efficiently. Any suggestions on how to solve or would it just be opening up the individual zone pumps and checking/ replacing the check valve. Also, Can you buy separate check valve or do I need to replace the whole pump

hot_rod

The new pump on the boiler, was it upsized from the former one? It looks like a high head model and could be overpowering the zone circs. A pic of all the piping, and boiler would help.

EzzyT

can can you post more pictures of the near boiler piping so we all can get a better picture of how piping was done in order to determine if it’s just the pump is the overall issue or some piping configuration is also the cause 

Jsipzner

The new pump is the same size as the older one (although it was always bigger than the individual zone pumps. Here are some additional pictures

Jsipzner

As I think about it more,  the original pump near the boiler was also a taco 0014 but it was black vs this new one which is green.  Not sure if there is a difference but the plumber who installed seemed to think it was the same

hot_rod

What is the model of the boiler? The boiler manual will tell you what that boiler pump needs to be. I thought those Weils used a 0011? It depends on the model.

Jsipzner

Weil Mclain Ultra 299-CT

Jsipzner

Looks like 0014 is the right one

hot_rod

If only there were a shutoff isolation valve on both sides of all those circs😗

Checking the checks, or checking for checks. In the circs, would be a next step.

Some installers tell me 5 years or so is all they get before the checks act up or fail.

They are in a turbulent condition close to the discharge, they get their brains rattled out.

12D, 12 pipe diameters of straight pipe between the pump and check is best practice.

Could be the camera angle, some of those look like a version that had the check on the suction side, bottom of the volute. What is the model number on the zone pumps?

Jsipzner

Zone pumps are each 007-f5-71fc. I'm thinking it must be the check valves as it's only happening on two zones and there are zones that are closer to the new pump that aren't giving me issues.  I suppose it's possible the new pump exacerbated the problem though. Do you think I need a plumber to replace these check valves which looked like they can be purchased for ~25 bucks. Last time I had the pump near boiler replaced,  I had a plumber do it because they mentioned needing to remove all the air from the line which I didn't know how to do.  

hot_rod

Probably best left to a plumber, as it will involve draining the system, refilling and purging each zone.
You might consider having new checks for all the pumps. Check pump model numbers, and manufacturers date there could be different check required.

Jsipzner

Got it,  thanks for all your help!

GrafHeating

Just a thought that will cost you money now and save it later. install valving to isolate each pump and install stand alone check valves. Also, consider a Spirovent. That will likely eliminate the need for purging

Dave H_2

To answer a couple of questions and then ask a couple:
1. There is no difference between a green 00 circ and a black one other than the color. Black means it came with a piece of equipment like in this case with the Weil McLain boiler. This is Taco's way of signifying it was sold to OEM companies.

2. There already is an air elimination device installed in the system.

3. Having IFC get stuck open in a 5 year old system and already replacing a circ tells me that we may need to look at water quality like maybe adding a mag dirt separator or treating the water chemically.

4. In order to verify that the IFC's are the culprit, you have some valves above the circulators, close one down down at a time (corresponding to the zones that are overheating) and observe if the temperature drops in the space as well as the pipe above it.

5. Yes you can replace the check valves in the circ, you do not need a new one. It will involve pulling the circulator out, removing the check valve (they don't come out easy and will probably break). Install the new one (o-ring down and push down until flush), reinstalling the circ and then purging the system.

6. While the system is open and water has been drained, time to inspect that water and this will be the best time to treat the water either mechanically of chemically.