Boiler going up to 215 Fahrenheit

Mr_H255

Hello, I’m going to try and make this quick. Let’s first start off with I do not know too much about boilers but I know how they work and what’s safe and what’s not. I do not know why type of boiler this is but I will add pictures showing the whole boiler. Just so you know it is quite old maybe 25-30 years. Recently about a month or two i’ve been noticing the boiler turning off and going up to 215 Fahrenheit. The pressure usually doesn’t rise above 20 PSI because we had someone come down and check out the boiler and he changed the setting for it. He also changed the setting for the boiler to stop at 170 Fahrenheit which sometimes works but sometimes doesn’t. Not only that, I’ve also been hearing loud water running through my pipes and thumps aswell throughout the house. Can anyone help me out?

Alan (California Radiant) Forbes

Typically, high water temperatures point to a pump no longer working. The boiler fires and there's not enough water flow to pick up all the heat. Thant will explain the thumps, but not the

loud water running through my pipes

Some pictures will help.

Jamie Hall

It would seem the pressure is adequate, but as @Alan (California Radiant) Forbes said the thumps, high temperature, and rapid turnoff suggest no or very little circulation. Air trapped somewhere in the system, something blocking flow (a valve partly closed somewhere? Damaged pump?

pedmec

As others have said it sounds like you lost water flow. i also might have why? have you seen a relief valve discharge. Did you or someone try purging your system and the feed valve didn't feed water? if you have air in your system you could have lost your water pressure. i know you said that the gauge never goes above 20 psi but are you sure its accurate and working. One thing about gauges is they fail a lot. i only say this because the thumping noise could be flashing of the water to steam but you would have to lose your water pressure for that to happen.

is this a cast iron boiler or mod con?

MaxMercy

The pressure gauge could be inaccurate (mine read over 70lbs all the time!), but the blowoff valve would also need to be bad if the boiler was going over pressure (long shot for both).

I would check the settings on the aquastat to make sure the high limit isn't set incorrectly. The noises could be air in the system. These could be two separate issues or they could be related.

Mr_H255

@Alan (California Radiant) Forbes I will send you pictures of the pipes in the boiler room because I am not sure what they are made out of, but from what I know this boiler did have a problem back then and that’s why at the front of it, it looks a little burnt.

Mr_H255

@pedmec  Recently when the plumbing guy came he opened the valve and like poured water out of the boiler I guess, to see if there was air in the system and there were little bubbles coming out so we did it a couple of times until the bubbles were almost not noticeable. Could that be an answer to your question?

Ironman

Can you take a pic of the label on the green Taco pump? Then move around 180* to the opposite side of it and take one there from a foot or two away from it.

Mr_H255

@Ironman Here are the pictures, I can also see if I can send you a video of the whole boiler. Also I just noticed, in the first picture one of the pipes is cut in half? 

Ironman

Can you take one of the pump with your back against the block wall facing the back of the pump?

Mr_H255

Take a picture of the back of the pump?

jringel

I would check the calibration on the aquastat see what temperature it actually shuts off at to see if its the control or just temperature stacking. I would also check the boiler temperature with a digital thermometer to see if the gauge is no good.

Mr_H255

I have no space to actually get behind the boiler but I took a picture of the back of it.

EBEBRATT-Ed

First you have to find out if the boiler is shutting off the burner at the 170 setting that you have it set for. If not you have a control problem.

It's not unusual to have the boiler and circulator shut off and for the temp to rise another 15-20 degrees from residual heat.

Ironman

The model number of the pump doesn’t indicate it, but if there’s an internal flow check in it, it needs to be removed. You don’t install flow checks with zone valves on a system. That would cause the thumping noise that you hear.

As mentioned, the accuracy of your gauge and aquastat need to be confirmed.

What type of radiators do you have?

Mr_H255

@EBEBRATT-Ed. Most of the times it shuts of at 170 and then it climbs up all the way to 210 then 215 then it goes down where it then starts up again. But just now, Im editing this, the boiler shut off at 185.

Mr_H255

@ironman I have baseboard radiators. I have a basement, and a first floor. Forgot to mention this is a 2 family house.

Mr_H255

it started up again and it shut off at 195. 

Jamie Hall

Where is the expansion tank in relationship (piping wise) to those pumps? Also any aur removal widget?

Just pouring water out of the boiler isn't going to purge the rest of the piping -- you have to do that with a really good flow, zone by zone.

It may be that the temperature overshoot you see -- which seems to be quite variable -- due to stored heat in the boiler when the pumps shut off, if they shut off with the burner. Some systems can be programmed with a post-purge for the pumps, which keeps them on after the burner stops and would pretty well eliminate the overshoot.

Alan (California Radiant) Forbes

I would start with ohming out the pump when there's a call for heat. It should draw .7 amps if it's working properly.

Do you know someone with a clamp meter?

hot_rod

As boilers age and get scaled or sludged up inside they tend to over shoot a bit. The heat in the metal of the boiler and in any deposits inside keeps transferring energy into the water after the burner is off
if the pump is operating properly, I might flush and clean the boiler. Run a hydronic cleaner for a day or so.

looks like some flame toll out has burned the front covers. It needs a good cleaning and service

HVACNUT

I don't think the temperature override is a big concern. A lot of WM boilers will override 20 or 30 degrees. 
It's got slow open zone valves so they shouldn't be an issue, but I'd like to see how it's all wired. There's a separate transformer by the zone valves. If the aquastat is an L8148E, then that also had a 40 va transformer. If it's wired in such a way where the circulator starts before the zone valve(s) are open, that will definitely make some noise.

hot_rod

At high temperatures like that be sure you are pumping away from the expansion tank. High temperature low pressure is a big invitation for cavitation. You want at least 10 psi at the suction side of the circ at above 200° temperatures.

Grundfos shows 7 psi required at 203°. 15 required psi at 230°

Pumping at the PONPC could result in low suction side pressure and set up some cavitation.

Mr_H255

Thank you everyone for the help, So far everything seems to be operating back to normal, thank you!

Sylvain

As far as I can see (eigth picture), you are pumping from the return toward the boiler (ok) but also toward the expansion tank which is after the boiler (third picture).
which is not good.
Is the pump on the other boiler pumping in the same direction?

If the three valves are closed there will be no flow in the boiler.