Dual zone boiler cycling when only operating 1 zone

[TurboMan]

Have a dual zone residential boiler that is cycling about every 1 1/2 minute if only 1 zone is being used. If both zones are used temperature stays steady 120. If I only operate 1 zone temperature goes to 135, hear a click, boiler shuts done a few seconds later, and temperature drops to 100. Then cycle begins again. From my research 135 seems like a low value for a limit. Boiler is approx 25 years old and was well maintained.

Any idea what might be wrong.

 

[Reach4]

Have a dual zone residential boiler that is cycling about every 1 1/2 minute if only 1 zone is being used. If both zones are used pressure stays steady 120. If I only operate 1 zone pressure goes to 135, hear a click, boiler shuts done a few seconds later, and pressure drops to 100. Then cycle begins again. From my research 135 seems like a low value for a limit.

Are you talking PSI???

 

[Sponsor]

 

[TurboMan]

Temperature. I think there is an issue with the pressure gauge - it's not moving.

 

[Fitter30]

Whats the brand and model number of boiler. What are you heating with fin tube ,radiators. Pressure reading of boiler? One or two story house?

 

[TurboMan]

Sorry for not responding sooner. Had a contractor over yesterday and he did something to the gauge so the pressure part works now and he raised the temp limit. Could not locate a brand so I attached the picture of the specifications. With only one zone running the temp will continue rising until it hits about 160 and then you hear a click and it shuts off. Once the temp falls to about 100 it turns on again and repeats the cycle. The cycle takes about 2 1/2 minutes now due to the higher temp limit. Currently have it shut off. I can get pressure reading tonight if needed.

 

[Fitter30]

The label has all the info. Brand Raypac 180,000 btu serial # 9410 made 10/94 . Minimum water temp is 105*.
What are you heating with fin tube ,radiators. Pressure reading of boiler? One or two story house? What happens with the other zone calling?

 

[TurboMan]

Dual zone system with plastic tubes (see plastic tubes.jpg) in the ground for both zones - one zone in the basement and one in the garage.

Got some real pressure numbers and sequence of events.
System off for 1 day. Only operating 1 zone (which is what we usually do). When system stops it is a full shutdown.

System at 30 PSI
Run 11 minutes.
Boiler electrical box clicks (see boiler box.jpg) - system shuts off - system 40 psi - 158 deg
Shut off lasts about 30 seconds
Temp falls to about 130 deg and 30 psi
Boiler electrical box clicks again - system starts
Runs for little over 2 minutes
Boiler electrical box clicks - system shuts off - system 40 psi - 158 deg
Shut off lasts about 30 seconds
Temp falls to about 130 deg and 30 psi
Boiler electrical box clicks again - system starts
Runs for little over 2 minutes
Boiler electrical box clicks - system shuts off - system 40 psi - 158 deg
again and again....

So every 2 1/2 minutes the system is re-starting.
PSI range 30 - 40 psi.
Temp range once warm is 130 - 158 deg

Thanks for any help. Contractor that was here said the system is running fine.
I am no expert but I think having the igniter running every 2 1/2 minutes is not good.

Thanks for any help.

 

[Fitter30]

Floor radiant how long are the tubing lenghts. What is the other zone feeding? Fin tube how many feet , air handler name plate ,radiator pics.

 

[TurboMan]

Zone 1 is the basement with a size of about 50 ft x 25 ft. Zone 2 is the garage with a size about 60 ft x 30 ft. The test I did above was actually with Zone 2 (garage). Previous tests were with Zone 1 with very similar results. We usually only use Zone 1.

Do not know the actual feet. Attached is a pic of the whole unit.

 

[WorthFlorida]

Check the expansion tank. There should be a schrader valve somewhere. A picture of its label would be helpful. The post the the pressure relief was opening because the expansion bladder tank was ruptured. This may not be your problem but if the boiler has a pressure sensor switch it maybe cutting off the system. (https://terrylove.com/forums/index.php?threads/pressure-valve-blow-off.90730/#post-651979)

Is this a new problem. Where you in the home last heating season? When the flame shuts down the circulators also turn off? I believe you stated a full shutdown. Any kind of controller for the two thermostats? During this event is the thermostat(s) still calling for heat?

 

[TurboMan]

Attached a pic of the expansion tank. The schrader value is on the bottom of the tank. Note the piece of paper on the tank that has 135 deg on it. That was the limit setting and the contractor changed it to 160. Seems like it is worse with the new setting of 160 deg.

We bought this home about a year ago and did not use this boiler. This issue is being covered by the home warranty. Yes, when the damper electrical box clicks (boiler box.jpg) the whole system shuts off (flame, circulator, etc). There are just 2 standard thermostats. Both thermostats are still calling for heat. They are set at 70 deg and it 64 in the rooms.

 

[WorthFlorida]

It's hard to say what is bad but do get a company out there that services these boilers. I'm sure you need to call your home warranty company on this. Since the entire unit shuts down, it more likely a safety device is activating.

Pressure could be getting too high and it shuts down but since it restarts itself is the strange part. You have a pressure relief valve on top of the expansion tank fitting but that doesn't seem to be blowing. It could be on the gas part of it where a sensor is not seeing the correct temperature or doesn't detect a flame. It looks like there is a electric damper on the flute, that could be failing. The expansion tank is easy to check out it is why I mentioned it.

You stated "Boiler electrical box clicks again - system starts". You need to find out what is activating the relay in this electrical box that is making the click. The picture with the boxes maybe controlling a valve to open or close to each zone if there is one circulator. Notice the clean copper push and fit couplers. The 24v transformer also looks new and it's all wired with thermostat wiring. Something may have been added recently by the last owner and this maybe the cause. Usually with two thermostats for one boiler, a TACO 502 unit or a equivalent is used and each zone would have it's own circulator.

Please update this post when this problem is resolved.

 

[Fitter30]

Need to check expansion tank pressure like worth florida said. Cool system to 100* or less turn boiler and pumps off. With a low pressure tire gauge 0-50 lb. If water comes out of scharder valve tank is bad air pressure shold be set same as boiler water pressure. Use a tire pump to adjust air pressure. There should be a metal tag on the relief valve that shows pressure rating. More than likely 30 lbs. Boiler you have is copper fined minimum water temp 105* Need model number of boiler. These boilers could have a flow switch because if flow stops and burner doesn't shut down immediately there trash.

 

[TurboMan]

Contractor adjusted the high setting to 130 deg which is 5 deg lower than it was originally. Boiler does stay running now but once it reaches operating temperature every so often you hear a click and it sounds like the heat flame is lower. And then in a short time it will click again and the heat flame sounds higher. I think that is because it is a 2 stage system? System will now stay running until the thermostat stops calling for heat. I brought up the expansion tank and the contractor immediately said no. Does this sound like a correctly running Raypak boiler? He was not too happy about coming back again.

We have been running the boiler for the past day and 1/2. Wanted to give it a little time to note what it is doing. Wife is happy. Guess that counts for something.

Also I noticed the damper on this boiler and the one we have in our pole barn is not functioning. They are both the exact same Raypak boiler. Never see it move from the open position to close when the system does a full shutdown. Is this something that I should call the warranty company about? Is a damper every kept always open on a boiler? From my research on boilers it does say that that is one of the most prone items to fail on a boiler.

Again, thanks.

 

[Fitter30]

Whats the pressure in the system now? By lowering the boiler thermostat 5* shouldn't change the thermostat operation to a two stage. There should be a metal tag on the relief valve showing what pressure the valve is set for whats that pressure. Someone needs to look at that dampers operation.

 

[TurboMan]

Pressure for the most part stays on 20. It bumps up a pound or two when in high flame mode. The system will stay running now until the thermostat tells it to stop. Max temp it reaches now is a little over 130. This is when the system goes to low flame mode and the temp slowly drops to about 120. Then it goes again into high flame mode and goes again to 130. Stays in high flame mode for about 20 seconds before going to low flame mode. This repeats indefinitely until the thermostat shuts if off. This with only 1 zone operating. Will run a test with both zones. I would expect it to run longer in high flame mode with both zones open.

Attached is a picture of the pressure relief tag. Says 30lbs. When the system high limit was set to 160 the pressure was going to 40. Shouldn't the relief valve have opened at 30?

 

[Fitter30]

Relief should have opened at 30lbs

 

[TurboMan]

Having trouble getting this repaired. Contractor told warranty company the boiler is working correctly. I told the warranty company the damper is not closing when the boiler turns off and that it is stuck open.

Exactly how important is it that the damper is opening and closing?

 

[Fitter30]

Damper is part of the boiler and it's efficiency. Will it make a difference yes helps keep the heat in the boiler when it cycles off. Damper isn't a aftermarket part as shown.
https://www.raypak.com/product/Raytherm-Hydronic-Boiler-0042-0180/

 

[WorthFlorida]

The lever on the pressure relief valve allows you to open and flush the valve. One of three things will happen. On opening it you'll probably see some rusty water then it'll clear. On closing, it will seal and no leaks, it will weep water because the seat has some corrosion and won't seal, or on attempting to open the stem will break off (I had that happen once).
https://www.watts.com/dfsmedia/0533dbba17714b1ab581ab07a4cbb521/24691-source/es-335-pdf. It has a warning paragraph.

The damper being open all the time is far better than stuck close. You'll need to know what controls it. If it's suppose to close on shut down, it's to minimize the heated air in the space from going up the chimney. Problem is to open on firing up the boiler, there needs to be some kind of sensor and control circuit to be sure it is open before ignition. It may have failed in the failsafe mode (open), or it never was hooked up to work.

Damper instructions start on page 11. Thanks on fitter30 for finding the manuals.
https://cdn.globalimageserver.com/FetchDocument.aspx?ID=C1E61B31-61AE-4C50-96AB-37275DE309DE