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View Full Version : boiler keeps going off/on, off/on....help!



TonyV53
12-06-2009, 07:41 AM
I just moved into my first house. 1950 Colonial with an old Stewart Warner boiler which uses oil, with hot water radiators of course. I first had a problem with the safety relief valve but resolved that by draining my water logged expansion tank.
Now I've notice a much bigger problem. My boiler will go on for about 4-5 mins, then turn off for 3-4 mins. The thermostat is set to 68 and its reading a current temp of 55 so its shutting off way before reaching desired temps.
On the boiler it reads around 12-15 psi when it turns off, which I understand is good, but the temp is 190 and it seems to go off when it starts going over 190. What am I missing?? Is there a valve not opened.

What am I missing, and how do I fix it?
Also, what should be my low/hi aquastat setting for this brand boiler?
Any help is appreciated. Please keep in mind this is my first home and first boiler I've ever had to try and fix so please excuse ignorance.
TonyV53

Peter Griffin
12-06-2009, 07:51 AM
It's not circulation. Probably the circulator is bad or you have a lot of air in the system. Since you opened it up to change the tank I would go with a lot of air first.

TonyV53
12-06-2009, 08:30 AM
So what should I do to try and get the air out of the system. Should I bleed the radiators? There is no way to do it off of the expansion tank, I looked.

msgale
12-06-2009, 10:16 AM
yes, bleed every radiator. If air is the problem, you will find a lot of it in them.
if you don't get a lot of air out, then you have another problem.

the boiler properly shuts itself off since the water is too hot. Once the water hits 190, you dont want it heated anymore. Your challenge is to find out why no new cooler water isnt being supplied to the boiler, and the hotter water pumped out to your radiators

TonyV53
12-06-2009, 10:45 AM
Got it.. Thanks a LOT. I'll do that and
check back to tell you how I made out, thanks again.

Doherty Plumbing
12-06-2009, 11:10 AM
The boiler is tripping on it's high limit because of lack of water flow. Could be air, could be a bad pump, could be a pump that has a clogged up impeller, could be a valve closed.

you need to:

1. Make sure all valves are open.
2. Make sure the pump is on and running.
3. Bleed your rads
4. Possibly pull the pump and inspect it further.

TonyV53
12-06-2009, 11:13 AM
Ok, I drained each radiator. Each of them had about 1 sec of air in them which
doesn't seem like a lot. I monitored the boiler it shut down again. This time got up to about 205 w/15 psi. The radiators are hot so I know the hot water is
circulating to some extent.
One thing to mention but I don't know if it really matters. I have 2 of the 12 total radiators cut off from the system. I found that they were cracked so I install shut off valves to one and the other I removed and just capped the 2 pipes.
Also, the thermostat doesn't seem to be reading the current correct temp. It's says it's 57 but I have a thermometer next to it that reads 47. I don't know if any of this is relivant.

TonyV53
12-06-2009, 11:42 AM
Rads are bleed and all valves are open, so trying to determine what the problem is with thr cirulator now, thanks!

Doherty Plumbing
12-06-2009, 02:37 PM
Ok, I drained each radiator. Each of them had about 1 sec of air in them which
doesn't seem like a lot. I monitored the boiler it shut down again. This time got up to about 205 w/15 psi. The radiators are hot so I know the hot water is
circulating to some extent.
One thing to mention but I don't know if it really matters. I have 2 of the 12 total radiators cut off from the system. I found that they were cracked so I install shut off valves to one and the other I removed and just capped the 2 pipes.
Also, the thermostat doesn't seem to be reading the current correct temp. It's says it's 57 but I have a thermometer next to it that reads 47. I don't know if any of this is relivant.

Has the system worked properly since you removed those 2 rads from the system? Depending on how it's piped this might be problem.

msgale
12-06-2009, 02:37 PM
one sec of air is nothing, either the air block is some trapped elsewhere, or it's not an air problem.

Radiator capped off: did this immediately precede the circulation problem? normally they are in parallel, but if you happen to have a series piped system, you may have shut it all down.

TonyV53
12-06-2009, 03:01 PM
I don't know if the system ever worked correctly. I just bought the house 3 weeks ago. When my boiler tech came over to service the boiler we then turned on and noticed rite away water coming from kitchen rad. I sent him home so I wouldn't get my billed racked up.
He had replaced a part which I can't remember the name of, but it's that safety eye that looks into the boiler and shuts down if it doesn't see light within 30secs. That cost me $350.
Anyway I installed shut off values in the basement going to that kitchen rad, only to find out one of the rads on 2nd fl master also had crack, so instead of installing shut off valves everywhere I decided to just cap that one until I can find replacements and get heat to rest of house before low temps start hitting 30's and I have a bigger problem.

So short answer is I don't know because it wasnt working long enough for me to monitor it.

Peter Griffin
12-06-2009, 04:07 PM
Well lets start with how it should be running

The aquastat controls the maximum temperature the boiler will reach. Called the high limit this control is usually set between 180 and 200 degrees with a 10 degree differential which is how many degrees the boiler will drop before the control operates again. When high limit is reached, the burners shuts off. during normal operation the boiler will come up to limit.

You may or may not have a low limit also. This sets the temperature that the boiler reaches before the circulator pumps will operate. It's purpose is to maintain temperature in the boiler if you have a tankless coil for domestic hot water.

You can check circulator operation either by checking for power at the circulator or listening to it. You should hear it run.

rmelo99
12-06-2009, 06:12 PM
Since you just bought the house 3 weeks ago, and have found some cracked rads tells me you must have purchased a foreclosure/bank owned house with frozen pipe damage.

Some pics would help us help you better. Since you said radiators many people assume the stand up kind, but being the house is from 1950 are you talking about baseboard kind of radiators?
If so then it is very possible that they are piped in such a way that you cannot remove/cap any individual unit without affecting the rest of the system.

Bring us some pics or a better description of how the piping arangement is in the basement.

patsfan78
12-07-2009, 05:50 AM
Post a couple pictures of the radiators themselves. If they are the baseboard type radiator and/or if they are piped in series, that is a potential problem when removing or turning off water flow to any radiator. We need to determine if the radiators, whatever type they are, are piped in a series (water must flows through one radiator to the next) or not. They shouldn't be piped this way if they are traditional radiators but it doesn't hurt to double check.

Just gotta start eliminating variables

TonyV53
12-07-2009, 08:33 AM
Yes, it was a forclosure bank owned property and of course they never told me about it if they knew. To boot, my inspector chalked it up as a broken fitting and that I just needed to fix that and I would be all set.

Anyway, here are some more details about the rads.
They are framed into the wall, so they only come out about 1 in from the wall with a steel cover. There are vertical 3/8 in piping going into each end of the rads, but 3 to 4 pipes go through the rad from end to end.

The one rad that I installed shut offs on, come off of a main copper pipe (about 1 1/2 - 2 in copper), so I installed shut off on the 3/8 piping branching off of that main pipe going to that rad.

Here are some pics of a rad I removed from the kitchecn wall.

its a Trane rad:
http://i81.photobucket.com/albums/j221/nasdaq53/trane10.jpg

from top view:
http://i81.photobucket.com/albums/j221/nasdaq53/rad10.jpg

from other end of top view:
http://i81.photobucket.com/albums/j221/nasdaq53/Trane_Radiator2.jpg

side view:
http://i81.photobucket.com/albums/j221/nasdaq53/Trane_Radiator9.jpg

rad is laying on its side:
http://i81.photobucket.com/albums/j221/nasdaq53/Trane_Radiator6.jpg

a side angle:
http://i81.photobucket.com/albums/j221/nasdaq53/Trane_Radiator4.jpg

I can take any other pics you want also.
Thanks again for looking further into this guys.

Doherty Plumbing
12-07-2009, 03:53 PM
That thing is OOOOLLLLDDDDD.

Anyway any more info (or pictures of your boiler room) to aid us in helping you solve why your boiler keeps tripping off on it's limit switches.

Peter Griffin
12-07-2009, 04:06 PM
Dem ain't radiators dem is convectors and they are always piped paralel off a monoflow tee system.

rmelo99
12-07-2009, 04:25 PM
Some pics of the boiler room piping would help us confirm your piping setup.

It will also help us to guide you to purge air...could be an air lock in the piping that needs to be purged out of a purge valve in the basement.

Think of the piping as one big loop with a start(supply) and finish(return). The water has to leave the boiler work its way thru the system and back to the boiler. The circulator moves the water. Sometimes the air blockage is big enough the circulator can't push it through. Need to confirm water is making it's way all the way around before you go looking for bad equipment.

One zone, multi zone? Any zone valves?

TonyV53
12-08-2009, 06:25 AM
Yes, the units are 1950 old. I will try to post some pics of the boiler room tonight but it won't be until later.
It's one zone, and I have a zone valve coming off the boiler.
Thanks again,

jadnashua
12-08-2009, 08:17 PM
If there's only one zone, why do you need a zone valve? Do you have an indirect WH?

TonyV53
12-09-2009, 06:32 AM
I don't have an indirect water heater if that's what you mean. I think what I mistaken for a zone valve is actually a pressure release valve. This is my first boiler and first home, so please excuse my ignorance.

Here are some pics the others guys asked for. Now that I look at them, they are not great pics . Not a lot of light in that room, but I can try to take some better ones if needed.

http://i81.photobucket.com/albums/j221/nasdaq53/boiler1.jpg

http://i81.photobucket.com/albums/j221/nasdaq53/boiler11.jpg

http://i81.photobucket.com/albums/j221/nasdaq53/boiler2.jpg

http://i81.photobucket.com/albums/j221/nasdaq53/boiler3.jpg

http://i81.photobucket.com/albums/j221/nasdaq53/boiler4.jpg

http://i81.photobucket.com/albums/j221/nasdaq53/boiler5.jpg

http://i81.photobucket.com/albums/j221/nasdaq53/boiler6.jpg

http://i81.photobucket.com/albums/j221/nasdaq53/boiler7.jpg

http://i81.photobucket.com/albums/j221/nasdaq53/boiler8.jpg

http://i81.photobucket.com/albums/j221/nasdaq53/boiler9.jpg

http://i81.photobucket.com/albums/j221/nasdaq53/boiler10.jpg

Peter Griffin
12-09-2009, 10:33 AM
Tony, the problems is one of three things ok maybe 4

1 - the circulator is not working
2 - the aquastat is either not sensing temperature, broken or not properly adjusted
3 - the flow check valve is stuck closed
4 - You have air in the system
5 - the heat anticipator on the thermostat is burned out

However, do yourself a favor and rip that piece of crap out of the house. It's taking the money out of your wallet by the handful. On a good day it might make 75% efficiency and that was 40 years ago when it was brand new. You can probably cut your oil bill about in half with a new boiler and outdoor re-set controls.

TonyV53
12-09-2009, 02:09 PM
I agree, it is a piece of crap, and I wish I could replace it but I don't have the money in my budget this year, and I have no way to fitting it in. It has to last me until next year.

About your 5 possible causes. Please keep in mind I'm a novice, if that when it comes to boilers. This is all new to me.

1 - the circulator:
Heat does get to the convectors and they do get hot, and house does get up to about 58-60 degrees, so I would think the circulator is working.

2 - the aqua stat is either not sensing temperature, broken or not properly adjusted:
I think the aquastat is working because I have it set to 180 hi/150 low.
It reaches about 190 with about 25-30 psi now, and then shuts off and started dripping water again from the safety relief valve.

3 - the flow check valve is stuck closed:
This is something I need to look into and check, but I'm not sure what I'm looking for.or how to do it.

4 - You have air in the system:
Another thing I need to try and check and try to verify. I just don't know how to go about check it or relieving it.

5 - the heat anticipator on the thermostat is burned out:
Very possiblyÖits and old manual Honeywell, so I wanted to swap it out anyway. I do that this weekend.

Thanks for your help. I really appreciate it. Is there any way you can give some direction on # 3 & 4??

Peter Griffin
12-09-2009, 03:13 PM
Number 3 - That red thing that says B&G on it, yep that think, it's the flow check valve, smack it with a hammer. Yes I said smack it with a hammer. Don't get carried away but give it a good rap or two.

Air needs to be purged at the convectors but if they are getting hot you probably don't have an air problem.

Try jacking the thermostat all the way up and see if it keeps running for a longer period of time. If it does, it's a bad thermostat. You could also bug the tt wires together at the primary control to bypass the thermostat and again, if it keeps on running it's the thermostat.

rmelo99
12-09-2009, 05:19 PM
I've seen worse....but it is old.

I had a similar b&g check valve on one of my old systems. I cant see the top but mine had a lever of some sorts that you can turn counter clockwise to

open the check valve...not a permanent solution but if that is your problem it will open the valve.

As to some convectors getting hot...heat rises so sometimes even if the circulator is shot the hot water will push cold water out of the rads and get them hot.

OLD gravity systems didn't have circulators and they worked.

Twisting the thermostat wires together is an easy fix to rule that out...I would not do it at the thermostat but rather short it at the boiler in case there is a problem with the wiring up to the actual thermostat on the wall.


Don't forget about Craigslist for a used boiler.
You are in CT so there are many people that sell boilers when they expand their houses or knockdown their old houses. I see them on CL all the time for cheap. I always look for gas ones but there are plenty of oil ones out there too. Sometimes free sometimes only a few hundred bucks!

TonyV53
12-10-2009, 09:33 AM
Awesome info guys. I will try the recommended troubleshooting and post back with the outcome.
I never even thought of trying CL for boilers. I tried finding replacement convectors there but never thought to look for boilers, thanks!

Thanks again guys. So glad I found this forum.

Doherty Plumbing
12-10-2009, 08:35 PM
Awesome info guys. I will try the recommended troubleshooting and post back with the outcome.
I never even thought of trying CL for boilers. I tried finding replacement convectors there but never thought to look for boilers, thanks!

Thanks again guys. So glad I found this forum.

Your gas valve could also be failing. You need to also check to see if you have voltage across the gas valve when it fails. If you do you know the gas valve needs to be replaced. If power is cut to the gas valve before it fails you know that there is a limit or safety that has tripped.

rmelo99
12-12-2009, 04:07 PM
Pretty sure it isn't the gas valve,seeing as his unit is an oil burner based boiler!

Saw this on CL and thought of you.
http://newhaven.craigslist.org/for/1503547502.html

Doherty Plumbing
12-12-2009, 05:02 PM
Pretty sure it isn't the gas valve,seeing as his unit is an oil burner based boiler!

Saw this on CL and thought of you.
http://newhaven.craigslist.org/for/1503547502.html

ROFL I forgot that small little detail! oops!

MAoilTech
12-15-2009, 01:51 PM
I'm a Master Oil Tech I'm Reading whats going on just adding my 2 cents

your aqua stat setting to high (This time got up to about 205 w/15 psi.) @ 30 psi and over your relief valve will let go
212 ur making steam if you have it @ 205 or 200 when your boiler hits that mark it will shut off but the temp will still go higher this will cuz banging in pipes pumps will go bad valve will leak in time normal range 160 low and 180 high def# 20 ur psi range 17-22 psi for water this will also go up when water is heated.

Replace you aqua-stat it sounds to me it not working if you can get a Hydro-stat it can read boiler water temp as well. also if you do not get ur hot water from you boiler such as Coil take the low side drop to lowest setting 120

Install a Purge set up above circ pump 3/4 x 3/4 x 1/2 c x c x f tee cant realy tell on ur pic if its 3/4 or 1 in but you get the idea
1/2 boiler drain and 3/4 ball valve. this will help with air in lines for now and later.

350.00 buck's for a Cad cell? highway Robbery :eek:
Also i didnt see a expansion tank in your pic's if you dont have one install one.
http://www.hydrolevel.com/pages/new.html

TonyV53
12-22-2009, 06:12 AM
Sorry it took so long to reply. Iíve been somewhat busy with painting and other things around the house, but I have been working on my boiler problem also. Not to mention insulating all my pipes and basement windows.

Anyway, so I smacked the flow check valve a couple of times with a hammer like recommended. I even manually opened the valve as a test. No difference, so I closed it back up and assumed its working ok.

I ran into another little problem. My safety relief valve has been leaking more and more water every day. It was getting to about 4 gallons a day. The valve was old, rusty and corroded, and it didnít have a nipple coming off it. So I replaced that this weekend thinking the valve was shot, and it was. No more leaking. I also purged all the convectors again, which all had about 20 seconds of air in them.

I also changed out the thermostat last week. Installed a Honeywell RTH6400D 5-1-1 (nice little thermostat). So I cranked the heat up to about 80 degrees. It was only about 45 degrees in the house at that time. I had the same problem. Boiler goes on for 4-5 mins, then shuts down for 4-5 mins, on and on and on. It takes about 1 hour or more just to get to 48 degrees.

I read the last post from MAoilTech about my aqua stat maybe being being bad, but Iíd hate to spend $350 on an aqua stat and finding out thatís not that problem.
My settings are currently 180 hi /150 low, and as soon as its gets around 190 it shuts down like clock work, so it would appear to be working but Iím a novice so I could be totally wrong.

Iím still working on replacing the two convectors that were cracked. Iím not sure if that will really make a big difference, but Iím going to see if I can order one today or tomorrow.

I'm not sure what else to test or try so any or recommendations are welcomed, thanks.

MAoilTech
12-22-2009, 12:04 PM
350? for aqua-stat? I think you mis-read it the tech that came to your house charge you 350 for a cad cell? not for the aqua-stat click link

http://www.google.com/products?hl=en&q=hydrolevel+cut+off&show=dd&sa=N&lnk=next&start=20

Hydrolevel Company 3150

fingerusarthriticus
12-22-2009, 07:39 PM
He had replaced a part which I can't remember the name of, but it's that safety eye that looks into the boiler and shuts down if it doesn't see light within 30secs. That cost me $350..

:eek: I am sorry, but are there no comments regarding the "easier than a lightbulb" light sensor replacement job coming in at $350!!!

rmelo99
12-23-2009, 08:58 AM
:eek: I am sorry, but are there no comments regarding the "easier than a lightbulb" light sensor replacement job coming in at $350!!!

Agreed, but that is just how some contractors are taking advantage of homeowners. I once had a problem years back with an oil boiler at one my properties that would not fire. Called out a local heating company who "correctly diagnosed" the problem as air in the single oil line. Cost me $95 for the diagnosis and he wanted $450 to run a new line set 10ft.

I paid him his $95 and sent him on his way. I called out the handyman my family has used for decades. I told him what the problem was. He saw they had used compression fittings on the copper line. He said that was a no-no. He took those off. Changed them to flare fittings. Used these little cans of compressed gas to flush the lineset, purged the air at the burner and got me running. All this on a weekend and he charged me $200. I was glad to pay him. I didn't even have to ask how much, he is pricing is not cheap but VERY fair.

He works exclusively on word of mouth and doens't take new customers. I only call him out when I am in a pinch because he knows his stuff. He's been maintaining the very old equipment at some of my apartments and keeps them running. Where most contractos would say replace it he knows how to service and maintain them so that isn't necesarry.

He does my annual service on 2 oil furnaces, nozzle, filter, oiling, vaccums out combustion chamber and never lets me down. If something needs to be replaced he does it and just tells me what I owe him.

wooson
02-06-2010, 08:51 AM
I'm not a pro but have been keeping a few boilers in our family running for 30 some years. I just joined this forum looking for several tips when I saw this problem. Maybe I missed it, but when you are trying to determine if your pump is pumping, do you hear water flowing out of the boiler? I can usually hear the pump kick on and if I touch (carefully) the pipe flowing out it gets hot fast. You can follow the trail of heat to see how far it goes and also feel the cool water enter the pump from the return. It's hard to bleed all the air without the pump running.

I've also used jumper wires to verify the pump runs. I didn't look at all the pics but if you closed valves that hadn't been used in awhile, a gate could be broke off blocking flow. Just a couple thoughts, good luck...

MAoilTech
03-13-2010, 01:01 PM
Agreed, but that is just how some contractors are taking advantage of homeowners. I once had a problem years back with an oil boiler at one my properties that would not fire. Called out a local heating company who "correctly diagnosed" the problem as air in the single oil line. Cost me $95 for the diagnosis and he wanted $450 to run a new line set 10ft.

I paid him his $95 and sent him on his way. I called out the handyman my family has used for decades. I told him what the problem was. He saw they had used compression fittings on the copper line. He said that was a no-no. He took those off. Changed them to flare fittings. Used these little cans of compressed gas to flush the lineset, purged the air at the burner and got me running. All this on a weekend and he charged me $200. I was glad to pay him. I didn't even have to ask how much, he is pricing is not cheap but VERY fair.

He works exclusively on word of mouth and doens't take new customers. I only call him out when I am in a pinch because he knows his stuff. He's been maintaining the very old equipment at some of my apartments and keeps them running. Where most contractos would say replace it he knows how to service and maintain them so that isn't necesarry.

He does my annual service on 2 oil furnaces, nozzle, filter, oiling, vaccums out combustion chamber and never lets me down. If something needs to be replaced he does it and just tells me what I owe him.

Some have Pride in what they are doing some do not if your handyman has his oil license all good the issue with non-license oil teck's come's down to insurance this happen to a lady in the town I live in she had non-license guy install a heating unit could not pull permit with no license 3 week's later the house burn down cuz of fire with there heating unit was not properly installed the lady Insurance company did not pay her for her lost.