Burnham boiler kicking off/on

For the past few months our boiler has been kicking off/on/off (almost 'stuttering' or misfiring I would say), near the time when it's about to kick off. In other words, it (I think) only does this minutes/moments before it actually shuts off (either due to the house reaching temp and the thermostat told it to turn off, or the hot water heater reached temp and told it to turn off). It (again, I think) doesn't happen when it first turns on or in the middle of running (i.e. if it turned on, and stayed on for an hour b/c the house was really cold, it would only happen right near the end of that hour).

I also noticed that the bucket is filling up a bit from the relief valve (probably an inch or so of water, whereas normally it's dry). I believe that means the expansion tank is either bad or needs to be otherwise needs to be fixed, but I don't know if this could at all relate to the boiler going off/on/off.

I'm going to have a pro come and look at/service it, but before doing so wanted to run it by the experts here, to see if you can advise as to what the issue might be/what it might cause to fix. I've had issues in the past with a (different) company telling me I needed to replace so many parts, so I want to have some idea of what the issue likely is in case this company tells me I need to replace thousands of dollars worth of parts...

The person that does my annual tune-up (whom I trust) is not available to come service it right now.

Thanks!

Pictures of my boiler for reference:

Hydronic boiler had air in pipes, now multiple valves leaking

 

I would have to start by asking is it just taking awhile to get to limit and than short cycling until it satisfies?

 

Hi. I'm not sure I entirely understand your question, but I guess the answer is no. The boiler is (as far as I can tell) working perfectly fine at all times (including for 1-2 hours in a row when the heat kicks on in the morning). The issue only occurs right before it's about to turn off (it seems to know that it's about to turn off, and then his stuttering occurs before actually turning off for a while, until heat is called for again). Once heat is called for again, it works perfectly fine until it's time to turn off again when it then stutters again. It doesn't always do this, but it's been happening more and more.

 

I’m not a boiler guy but I do my own maintenance. As far as I know boiler shutdown sloppiness like that can be caused simply by lack of service. The nozzle and filters need to be changed periodically. I do it once a year and I don’t think you can go too many years without doing it.

Also, I think if air is getting into the oil line that can cause sloppy shutdown. Not sure how common that is though.

If you haven’t had service for a long time maybe that’s the problem and that could also explain why your pressure is going up (losing water at relief valve). The pressure tank may need air if you haven’t had service for a long time.

I think you can check the pressure tank yourself. I thought there used to be a sticky on this forum that told you how to check/add pressure to the tank, but I don’t see the sticky now. You can probably google and find the instructions. I don’t have a bladder tank so I’ve never had to do that procedure.

 

Your 2017 post photo shows a boiler with a control on the front of the boiler. The control turns the boiler on or off based on state of control signals from the house thermostat or the aquastat monitoring the water in the boiler used for the circulating hot water heating system. There could be a third control signal from another aquastat if that is a domestic hot water tank near the boiler and uses the boiler to heat its water . Since any of the 2/3 control signals turning on/off rapidly could cause the condition you mention, my approach would be to take steps to only have one control signal controlling the boiler through a burner on to off cycle. One of the 2/3 signals should cause this condition. The source should be repaired. Since this is usually beyond a DIY effort, I would contact a reputable HVAC company, not the ones you used in 2017.

 

Thanks everyone. I'm calling a reputable hvac company today (definitely not the ones I used several years ago).

 

You have multiple zones so it is possible that when one zone shuts off another one is starting or multiple zones satisfied at almost the same time but I wouldn't think this coincidence happens every time.

Your heat is controlled by thermostats and your hot water is controlled by an aquastat on the tank so although they do the same job they are different so I believe they can be eliminated. The common denominator is the boiler aquastat control.

What you can try is to turn everything down so nothing calls and then turn one up at a time until satisfied and see what happens.

I have seen your problem with zone valves but not circulators.

Hope this helps a litttle.

 

Thanks. I should add/clarify (as I didn't really do so above), that this happens both when the heat is about to kick off, but also when the heat is not in use, and the boiler runs to heat the hot water tank.

It's definitely not related to 1 heat zone going off when another goes on, as this is a brand new issue that never used to happen.

Also, as just noted, it happens both in relation to the heat and the hot water heater, so again, I don't think it's related to a specific zone either.

Thanks again.

 

The isolation approach works with turn on or turn off.

 

If they are Taco 555 zone valve powerheads, little boxes le green or gold pyramid devices on the valves on pipes, they will sometimes do this due to the heat motor going bad.

 

Does 03/2005 mean that my boiler is about 18 years old? Or is that something else (and it just looks like a date)?

Thank you!

 

I had a (hopefully) more reputable company come out, and of course we couldn't duplicate the issue when he was here. He said to call again/try to take video if/when it happens again. He didn't mention anything about the 2/3 control signals nor did I remember to mention it.

Separately, he did provide an estimate for the expansion tank (and some other related items, I think). Does this seem reasonable ($1,538.67 including tax):

 

What brought up the replacement of all these parts. If your relief valve only drips after the boiler is reaching temp then I would check the expansion tank.

The relief valve is doing its job if it leaks at 30 psi and then stops after pressure drops. If your boiler maintains a constant pressure when off and does not climb your auto feed/ backflo are fine.

It sounds like you just need to check or replace your expansion tank and to do that you can isolate your system from your boiler. Open up your boiler relief valve for a few seconds to drain the water to a point below the tank so there would be no or very little refilling and most likely no bleeding so you can eliminate the cost of draining & refilling the system. When the tank is replaced and the cold water valve is turned back on the feed valve will add the little water needed by itself and most likely will be fine.

In my opinion for the prices quoted you are being taken advantage of. The way your system is set up even if everything they listed was needed it could be completed in way less than 2 hrs. time.

I would get a couple of quotes or just have them change the expansion tank and add a shutoff between the tank and the boiler for future tank maintenance. All these parts and the leak have nothing to do with the on/off situation.

Just my opinion, hope this helps.

 

Thank you. I'll definitely get a second opinion first, and/or just get another company to do an annual tune up and see if they say anything to me.

The only reason he did the estimate is I pointed out the water in the bucket. I don't know if he then quickly checked anything or just started naming parts that would need to be replaced along with the tank and/or in conjunction with trying to solve the on/off issue.

Thanks again.

 

What he did was price everything that could possibly be connected with the drip and hope for the best that you would say GO AHEAD and he would have had a great payday for a couple hrs. work with traveling.

3493-075-BT1 - Taco 3493-075-BT1 - 3/4" Brass Combination Boiler Feed Valve & Backflow (NPT x NPT) (supplyhouse.com)

Above is just an example of the cost the one item on the list and what they are charging you. You can find all the other parts on the same sight.

 

Thank you again. I will definitely be getting another opinion/estimate... but likely just getting a tune up first and seeing how it goes from there.

 

They should be done every year. The nozzle, filter, pump screen (if any) brushing if needed and efficiency test done, This will not address the drip but most likely just the replacing or recharging the tank will.