Any boiler techs here?

[dieseldog]

Sean, you've definitely got an electronic/electrical problem--probably some bad relay that is "falling out" of the circuit, which then resets itself--trying to engage again. It's possible you could have a bad gas valve that doesn't allow the system to "prove" itself; however, that is less likely, as you've mentioned that the system does run for five minutes and heats up quite a bit before starting the short cycle behavior.

My father--a retired plumber with MUCH experience in the plumbing/heating game thinks you need to enlist the aid of an electrician who is knowledgeable about electronic controls specifically. It's true that plumbers may have installed the complete system ten years ago--no surprise. It takes less knowledge to install a system as opposed to de-bugging/diagnosing the most complex portion of the system--the controls.

Another thought--why not contact the system's manufacturer and talk them through your difficulty. They may very well have had other reported instances of their equipment behaving in this manner. A sharp tech on their end might well be able to talk you through this yourself. Just a thought.

Good luck!

 

[SteveO]

A couple things:

1. You don't have a thermocouple at all in that system. It uses a flame rod.

2. Your gas valve is likely operating fine if it successfully relights when the ignition system kicks in. Make sure you wipe the ignitor clean though (while it's off. They produce 10-30K volts. )

3. Try manually opening all your valves and then call for heat and see if it's still cycling. You could have a problem with a valve not allowing high enough water flow and that's why your high limit is tripping.

4. Listen to the pump to see if you're actually moving water. If it's noisy or gurgling you may have an air pocket causing the pump to cavitate and not move water, thus causing the overheating.

5. Have you noticed one area of the house is not heating as well as it did before the problem started?


If you were closer I'd swing by and get you sorted in twenty minutes or less but that's probably not going to happen. Troubleshooting is alot easier when you're actually at the unit. Keep us posted. ....Steve

 

[yooper]

Thanks Steve. I'll try all that tonight. The pump seems quiet but there is noise elsewhere in the house since about the same time. When I asked the plumber about it he said it was normal noise. Haven't noticed heating problems anywhere, but there are two zones that have had very little use since we've been here. I will make sure I open those up...

Will report back...

 

[Degnol]

Yoop, is your recirculating pump, aka "B&G" unit working properly? My garage floor is heated with warm water boiler heat and mine did that when the pump was bad. If you are zoned, you may have more than one pump? Dunno. Mine has a small volume high pressure to feed the circuits and a high volume low pressure to recirculate the boiler.
That's the only help I can be. My mechanical room looks like the bowels of a U-boat

GL

Ed

 

[yooper]

OK, just opened all valves manually and it fired up then after about 3 minutes it started cycling again. I turned the high limit up 10 degrees while it was doing this, with no effect.

I'm beginning to suspect the pump. It's awfully quiet. When everything else is completely off I can hear some water gurgling by in there. Doesn't seem to be vibrating much either. It's getting power from the control box, so I know it should be on. The pump on the In-Floor unit is much louder and vibrates a lot more...

I also discovered that one of my zone valves is leaking.

Thanks guys, I will keep investigating...

 

[FJ809496TLC]

Do you have a flow switch in the system? Check your high limit/differential switch/thermostat to see if it is opening prematurely. Your temp differential might be going out. You need a test meter or jumper wire to do this. Are you having heating problem in some areas?

 

[yooper]

Do you have a flow switch in the system? Check your high limit/differential switch/thermostat to see if it is opening prematurely. Your temp differential might be going out. You need a test meter or jumper wire to do this. Are you having heating problem in some areas?

I have meter and wire. How do I test this?

Haven't noticed any heating problems.

 

[FJ809496TLC]

Make sure you have a thermometer to read your water temp. Set your high limit to your desired temp., Let say 160 deg. F, put the leads of your meter to terminal B and R it should read zero volt till the switch opens up.Double check this by leaving one lead to B then R and the other lead to neutral or ground, if it's close it should read voltage. High limit will stay close till it reaches the set temp then it will open up turning the gas valve off. The differential switch will close the circuit when it reaches the preset differential temp.let say 20 deg. F. which in this case is 140 deg. F

 

[BigGun J]

I would suspect the flame rod. Two things could be happening. When the boiler fires it is pulling the flame off the rod and then the system tries to relight "your style of ignition" Generally there is a view port to see the ignightor. When the sytem starts to short cycle, take a butane torch and maintain a flame on the flame rod. You do not have to get, or keep it red hot. Just maintain the flame on the rod and see if your boiler will maintain flame. Hopefully it will. Then I would clean the flame rod as previousely mentioned and check its position. I would suspect your ignitor wire may need to be replaced. It is just like a spark plug wire and it creates to much resistence over time. Also, if while viewing the flame "wear safety glasses? see if the flame is rolling and lifting off the burners and drafting the pilot off the flame rod. Does your system have a draft control on the chimney?

Jim

 

[yooper]

Thanks guys. I'll check all those things this weekend.

I don't think the high limit switch is doing it - the first time I checked across the B and R terminals there was never any voltage across them, i.e. the circuit was closed the whole time. I will check again and double check and watch the water temp.

The flame rod and ignition wire are prety new. They were replaced a year ago with no effect on the problem.

There is a fan on the chimney. It turns on before the gas valve opens and stays on for a minute after the gas shuts down and then closes a damper when it shuts down. During this rapid cycling the fan is just staying on.

I will try to watch the pilot flame, but that doesn't really make sense to me as the problem doesn't happen until everything gets pretty hot - I will check it out though.

My suspicion is that something gets hot, maybe gets distorted from the heat, and then causes one of the switches to open...

Will report my findings...

 

[SteveO]

The other thing I would check is the pressure switch. It's job is to confirm to the vent fan that there is a place for the products of combustion to go. If you're getting poor air flow through the boiler the switch may open. The gas will shut off and as soon as the pressure switch is closed the system will try to relight. I've had to reaplce faulty air prove (pressure) switches before although it wouldn't be the first thing I'd check on your system. You can check it with a voltmeter and you should see it close when the vent fan starts and stay closed the entire cycle. It may have zero volts across it while off, then only read a voltage for a brief second before closing. Keep us posted. .....Steve

 

[whodat]

meh



(sorry Yoop, had to do it)

 

[yooper]

The other thing I would check is the pressure switch. It's job is to confirm to the vent fan that there is a place for the products of combustion to go. If you're getting poor air flow through the boiler the switch may open. The gas will shut off and as soon as the pressure switch is closed the system will try to relight. I've had to reaplce faulty air prove (pressure) switches before although it wouldn't be the first thing I'd check on your system. You can check it with a voltmeter and you should see it close when the vent fan starts and stay closed the entire cycle. It may have zero volts across it while off, then only read a voltage for a brief second before closing. Keep us posted. .....Steve

I've already tested the pressure switch and it works perfectly. I also disconnected it and put a jumper across the wires, removing the switch from the equation, with no effect on the rapid cycling problem.

thanks again. I probably won't be able to play with it again until Sunday night, but I will report any findings...

 

[FJ809496TLC]

yooper, when you say short cycling, do you mean that boiler shuts off before it reaches the setpoint and then restarts again several times till it does or does it reaches the setpoint then shuts off(satisfied) and then try to restart itself when the water temp is below the differential setting? Did you check if there is a flow switch(field installed) on the piping? Your high tension wire looks bad and can cause problem also. Verify that you have 24V all the time on your intermitent pilot while the boiler is short cycling if you do, the problem could be on the flame rod/high tension wire, flow switch(if there is one) or the intermitent pilot itself. If you're loosing 24V to your intermitent pilot terminals then the possible culprit could be the 24V stat or rollout switch assuming the high limit and the pressure switch are good. Good luck.

 

[toolmandave]

i have a crown aruba xe that i could use a little more info on. no owners manual, of course does the circulator pump only run when the burner is on? or is it controlled by a temp switch? and how would i go about adding more heating elements onto the system???

 

[yooper]

ooh thread revival and timely too!

My original problem was fixed by a new plumber by replacing pretty much the entire control system twice, we never did figure out what the deal was, probably the main circuit board and probably had two faulty replacements. My gas use went down about 20% after fixing it.

But now I have a new problem. The boiler is putting a little bit of water out of the overflow pipe every single time it fires up. I'm pretty sure this is not normal and it's a PITA because the floor is always wet.

Is there something simple I can do, add water, burp it somewhere, pressurize the overflow tank? Or should I call the plumber for an expensive analysis? It's pretty much due for annual maintenance anyway...

 

[yooper]

i have a crown aruba xe that i could use a little more info on. no owners manual, of course does the circulator pump only run when the burner is on? or is it controlled by a temp switch? and how would i go about adding more heating elements onto the system???

I'm pretty sure the circulator pump and the burner are independent.

When a thermostat calls for heat the circulator pump turns on and sends hot water into that zone.

The burner thermostat is a separate one and it fires the burner whenever the water in the system gets below the set point. Usually this only happens when the pump is on, bringing cold water back into the system, but not always.

I think you just have to get a bigger boiler if you want more capacity.

 

[FJ40_owner]

ooh thread revival and timely too!

My original problem was fixed by a new plumber by replacing pretty much the entire control system twice, we never did figure out what the deal was, probably the main circuit board and probably had two faulty replacements. My gas use went down about 20% after fixing it.

But now I have a new problem. The boiler is putting a little bit of water out of the overflow pipe every single time it fires up. I'm pretty sure this is not normal and it's a PITA because the floor is always wet.

Is there something simple I can do, add water, burp it somewhere, pressurize the overflow tank? Or should I call the plumber for an expensive analysis? It's pretty much due for annual maintenance anyway...

Do you have a hot water tank and is it pressurised? Do you have a T&P valve. (Temp and Press)? This could be bad or have a coroded seat.

 

[yooper]

Do you have a hot water tank and is it pressurised? Do you have a T&P valve. (Temp and Press)? This could be bad or have a coroded seat.

I don't think there is a hot water tank, nor is the system pressurized, but I'll look tonight.

So maybe just the overflow/safety valve is bad? I'll check that out tonight and clean or replace it if it looks corroded. thanks!

 

[Toyo FJ40]

Your system has to have an expantion tank. It will be either hanging from a pipe or air vent or there will be a tank at the ceiling. If it's a hanging tank than it needs to be refilled with air or replaced. There will a tire stem on the bottom and if you push it and water comes out than it's junk and needs replacement. If water doen't come out it need to be charged to 12 PSI. If it's a tank at the ceiling you need to turn off the valve on the pipe that feeds it and hook a hose to the tank and drain it completely. Shut the drain and open the valve to the tank back up and the boiler feed should refill it(about 1/3 is where it should be) The old style tanks need to be drained about every 2 years (water absorbs the air over time).

Hope this helps.
BTW the old problem sounded like a bad roll out switch.

Kevin