Help! My Hydronic heating system keeps destroying circulator pumps.

delay1968

Moved into my house about 8 years ago and for the first several years the heating was perfect. Dead quiet and efficient. It is a hydronic system with 7 radiators of varying sizes, a Burnham furnace, and had a B&G 100 series circulator.

Things have never been the same since a few years ago when we were having our bathroom renovated and the demo caused a leak at one of the pipe joints for the radiator in the bathroom. The plumber was not available but walked the contractor through a way to lower the system pressure and still have the heat work until he could come and do a proper fix. That seemed to work and I was told soon after that everything was back to normal. Things between the contractor (and the plumber, who was his cousin) went bad soon after and of course so did the heating system. The B&G pump started leaking and the system pressure was extremely low.
I had a different plumber come in and he replaced the circulator with an equivalent Armstrong version with identical specs. There were no valves around the pump so the system was flushed and refilled after changing pumps. Within weeks the pump started squealing when shutting off. Soon after that it started rattling and making all kinds of crazy noises. The plumber came back and replaced the new armstrong pump with an identical replacement which got us through the rest of that winter. He had to drain it again but put valves around the pump this time. Then last year, within a few weeks of starting up the system, the same pattern emerged starting with the squeal and then the rattling. Put a new one in (Armstrong sent one as a warranty replacement) and same thing, but we just dealt with it to get through the winter.
This year, I got a new B&G as the plumber and I both seemed to think there was an issue with the Armstrong pumps in our system. He also found the pressure regulator wasn't up to snuff and replaced that. But within 2 weeks of putting the new B&G pump in, it is already squealing.
I have already put over $1000 into fixing this issue and have clearly gotten nowhere. What are other things I should look at?
The pump feeds right into the furnace. It has a steel expansion tank coming soon after the output of the furnace. Attached is a pic that shows the basic setup (though there is now a B&G pump and isolating valves around the pump).

JohnNY

I'd imagine you've got some debris floating around in your water. A good system flush and some water treatment would likely go a long way in resolving this for good. So would a Y strainer.

hot_rod

Are they putting the oil in the 3 different oil cups?

The spot on the floor indicates past pumps may have been oiled, or over-oiled

JUGHNE

What pressure is it set at when cold?

SuperJ

If you have/had a leak and constant makeup, you could have mineral issues that can lead to all kinds of failures. Since your problem started with a leak, I suspect this. Probably need to test the TDS, clean and flush the system and fill with properly treated water after all leaks have been repaired and pressure tested.

It may not be the root of your problem, but you shouldn't be pumping towards the expansion tank. The tank/makeup should be on the suction side of the pump to maintain a constant reasonable suction pressure on the inlet to the pump.

Ideally you would:
-pipe return right in the boiler (no pump yet)
-go thru the boiler
-have your air separator, expansion tank and makeup assembly
-and finally after all that pump away from the boiler towards the house.

Has your expansion tank been properly setup? What device are you using to control the static pressure in the system? (I see a sloppy looking copper line tee'ing into the outlet of the boiler, is that your makeup?)

Do you have any control valves in the system that might be causing occasional deadheading?

After you resolve the source of your problem, you may want to review the circulator selection, and consider switching to an ECM wet rotor pump.

delay1968

hot rod said:

Are they putting the oil in the 3 different oil cups?

The spot on the floor indicates past pumps may have been oiled, or over-oiled

The Armstrong pumps were "maintenance free" so no oil added. The new B&G currently in the system, was definitely oiled. I saw him put most of the tube that came with it in.

delay1968

JUGHNE said:

What pressure is it set at when cold?

Not sure, will have to check when I get home.

delay1968

SuperJ said:

It may not be the root of your problem, but you shouldn't be pumping towards the expansion tank. The tank/makeup should be on the suction side of the pump to maintain a constant reasonable suction pressure on the inlet to the pump.

Ideally you would:
-pipe return right in the boiler (no pump yet)
-go thru the boiler
-have your air separator, expansion tank and makeup assembly
-and finally after all that pump away from the boiler towards the house.

Has your expansion tank been properly setup? What device are you using to control the static pressure in the system? (I see a sloppy looking copper line tee'ing into the outlet of the boiler, is that your makeup?)

Do you have any control valves in the system that might be causing occasional deadheading?

As far as the setup goes, I don't doubt that it might not be ideal, but it was operating perfectly for years since I moved in and presumably a few before I moved in (the date codes indicated the furnace and pump were already a few years old), so it is capable of running properly without destroying the pumps.

As far as your other questions go, those are a bit beyond my scope. But not visible in the pic are the pressure regulator and backflow preventor (I think) which are on the smaller line bringing the water into the system. The regulator is brand new and the screen on the other piece was checked and cleaned. I don't believe the plumber has done anything to set up or check the expansion tank.

delay1968

SuperJ said:

If you have/had a leak and constant makeup, you could have mineral issues that can lead to all kinds of failures. Since your problem started with a leak, I suspect this. Probably need to test the TDS, clean and flush the system and fill with properly treated water after all leaks have been repaired and pressure tested.

I think you added this paragraph while I was responding to your initial reply. This sounds like it might be up the right alley. The pipes and radiators are over 100 years old so in addition to minerals from the water I am sure there is other crap in there. Though the system has been flushed a couple times for the first two pump replacements it was not flushed this last time. I live in Brooklyn, NY and I don't believe the water is particularly hard here but maybe I am wrong about that or maybe that doesn't matter.
In any case, I believe the leaks are all good now, but how complicated is it to flush the system and make sure it is clean and then treat the new water? Seems like my current plumber might not be the one to do this.

SuperJ

It looks like your system was a converted gravity system, so it should have a pretty low pressure drop. Which should let you get away with a less than ideal setup on your expansion tank and makeup. But still requires proper setup.

If your a bit handy setting your tank pressure isn't too complicated or difficult. Luckily, you have an isolation valve to let you spin off and setup the tank with draining the system.

SuperJ

The system pressure should be the first thing you check. Ideally the pump inlet pressure while the pump is running.
It's possible that the system pressure was so low the pumps were drawing negative pressure on the inlet which allows cavitation to easily occur. Cavitation can cause premature death of pumps.

As far as flushing goes, maybe educate yourself with some of the coffee with Caleffi videos on youtube. They have one on water quality. https://www.youtube.com/watch?v=vS21nxw6nX0

delay1968

SuperJ said:

The system pressure should be the first thing you check. Ideally the pump inlet pressure while the pump is running.
It's possible that the system pressure was so low the pumps were drawing negative pressure on the inlet which allows cavitation to easily occur. Cavitation can cause premature death of pumps.

As far as flushing goes, maybe educate yourself with some of the coffee with Caleffi videos on youtube. They have one on water quality. https://www.youtube.com/watch?v=vS21nxw6nX0

Thanks so much. I might be a bit out of my league here (and don't have a way to check pressure other than the guage on my furnace which is obviously not what you are talking about) So I am probably going to have to get someone else in here to look into all this. Sounds like this could get expensive (on top of the money I already spent). Is there someone besides a plumber I should look for? Hard to tell if someone is really a specialist in this particular type of system from ads/websites.

One thing I didn't mention is that some of the water I saw when the system was being worked on definitely looked dirty so would that imply it is more of a water quality issue rahter than pressure issue?

JUGHNE

Post a picture of the boiler gauge.
It should show the pressure.
You want to observe it cold/cool with out pump and burner on and see what happens when you start burner/pump.
Also watch if pressure rises as the temp does.
How many stories tall is the house?

GBart

Squealing old style circulators........

RULE 1

DO NOT USE STANDARD MOTOR OIL, YOU MUST USE OIL SPECIFICALLY FOR THE PUMP OR NON- DETERGENT 20W MOTOR OIL, STANDARD MOTOR OIL DOES NOT LUBE THESE IT CLEANS THEM AND THEY SQUEAL

ALSO NOTE*** the motor does not need more than a few DROPS per year, the pump section you can load up, that's what your problem is, the wrong oil

delay1968

JUGHNE said:

Post a picture of the boiler gauge.
It should show the pressure.
You want to observe it cold/cool with out pump and burner on and see what happens when you start burner/pump.
Also watch if pressure rises as the temp does.
How many stories tall is the house?

Will try to do this tonight when I get home. Luckily it's not that cold today. It is a 2 story house with a basement. The system is in the basement.

delay1968

GBart said:

Squealing old style circulators........

RULE 1

DO NOT USE STANDARD MOTOR OIL, YOU MUST USE OIL SPECIFICALLY FOR THE PUMP OR NON- DETERGENT 20W MOTOR OIL, STANDARD MOTOR OIL DOES NOT LUBE THESE IT CLEANS THEM AND THEY SQUEAL

The Armstrong pumps were sealed, maintenance free and the new B&G pump was just installed less than 2 weeks ago and lubricated with the supplied oil.

hot_rod

Looks like sealed bearings are now common, and posted mentioned it was that style/

Armstrong has ECM motor, 3 piece circs available, fixed speed. nice to know if you want to stay away from wet rotor style.

GBart

Anyone ever suggest that you insulate your pipes??? they're huge and a major waste of energy, plus you shouldn't even have that circulator, it's old school.

kcopp

On another note the vent damper is installed wrong,
It should be on top of the vent hood not the boiler.

HomerJSmith

Why do you think your B&G series 100 failed? Did you take it apart? I've repaired many series 100's and have yet to see a motor that was lubricated fail. I mostly saw the spring couplings fail or the ceramic seal fail. There were 3 lubrication point on the 100's, 2 on each end of the motor and 1 on the pump. I would have taken the volute apart and looked at the impeller. I think I would have put a Caleffi Dirt Mag on that sys.

The 100's as I recall has about 8' of head and a very flat pump curve, which is why it was used with zone valving by so many manufactures.

I would follow the advice about moving the expansion tank to the inlet of the pump and I would want to check the air charge on the tank, too. The air charge should be about 12 psi for a 2 story house. You want the maximum amount of sys pressure at the inlet to the pump, so move the expansion tank to the inlet. Also, take the advice and move the damper to the outlet of the vent hood.

It looks to be a Burnham boiler so remove the front cover and look at the pressure gauge when it's cold and tell me what the pressure gauge says.

I still want to know why you think the pump failed. As far as what the customer says, I say "trust but verify".

Zman

What model is the armstrong circ?

delay1968

Ok so the pressure when off for an hour and (almost) cold is about 16 psi. After turning it back on, cranking the thermostat and letting it run for a bit over an hour, the temp was close to 150 and the pressure about 23-24 psi. I also noticed that the expansion tank seemed completely empty when knocking it with my knuckle. No idea if there is any pressure in it.

delay1968

> @Zman said:
> What model is the armstrong circ?

The armstrongs were the S-25. But I am now back to a B&G 100.

Zman

The model?

delay1968

Zman said:

The model?

Model S-25# 174031MF-013

delay1968

HomerJSmith said:

Why do you think your B&G series 100 failed? Did you take it apart? I've repaired many series 100's and have yet to see a motor that was lubricated fail. I mostly saw the spring couplings fail or the ceramic seal fail. There were 3 lubrication point on the 100's, 2 on each end of the motor and 1 on the pump. I would have taken the volute apart and looked at the impeller. I think I would have put a Caleffi Dirt Mag on that sys.

The 100's as I recall has about 8' of head and a very flat pump curve, which is why it was used with zone valving by so many manufactures.

I would follow the advice about moving the expansion tank to the inlet of the pump and I would want to check the air charge on the tank, too. The air charge should be about 12 psi for a 2 story house. You want the maximum amount of sys pressure at the inlet to the pump, so move the expansion tank to the inlet. Also, take the advice and move the damper to the outlet of the vent hood.

It looks to be a Burnham boiler so remove the front cover and look at the pressure gauge when it's cold and tell me what the pressure gauge says.

I still want to know why you think the pump failed. As far as what the customer says, I say "trust but verify".

Well, the seals definitely went as it was leaking, the heat was barely working and it was making a heck of a lot of noise.

I am the homeowner, and while pretty handy, not well versed enough in this stuff to know what to look for if I were to take the pumps apart.
Also, like I said, I don't doubt that there might be a better way to set this system up but I am pretty confident that the problem I am having is not a result of the setup in that it worked flawlessly for the first few years I was here and probably before I moved in as the furnace and pump were already a few years old when I got here.

I posted separately that the pressure cold is about 16 and went up to 23-24 when the temp got up to 150 after an hour or so.

Zman

The circ is appropriate for the application.
I would say either low pressure or bad water chemistry.
Do you trust the pressure gauge? You could thread one onto the boiler drain to confirm. What do you know about the water quality?

HomerJSmith

That is too much of a pressure rise for 150 deg from a 16 psi cold reading. You should probably see a 2 to 3 degree rise.

I think that the expansion tank is low on air and becoming water logged or over inflated.

Move the tank to the input of the pump and when it is disconnected, check the charge pressure on the tank and set the charge pressure to the static pressure of your system + 5 psi. Every 28" in elevation is equal to 1psi.

Static pressure is the weight of the water in your system pressing down on the boiler from the top of the highest radiator in your system. That's what you measure from the top of the boiler to the top of the highest radiator.

As Zman says, you can verify the tridicator with a hose bibb pressure gauge with a 30# gauge on it instead of the 150# gauge that comes with it. Just screw it on a boiler bibb and open the valve to read it.

Tridicators fail when you have a dirty system.

What I would look for in taking the pump apart is to look at the outer edge of the impeller and look for pitting or corrosion which would indicate cavitation.

Sometimes you can look into the outlet of the pump with a flashlight and see the outer edge of the impeller and look for pitting etc.

Jamie Hall

There is an old saying which could be modified to apply: fool me once, shame on you. Fool me twice, shame on me. The modification here is -- you have had three (?) pumps fail. The odds of its being a pump problem, then are nearly zero. Do some of the piping changes suggested and get the expansion tank working properly -- it isn't -- and, just for safety, put a pressure gauge tap at the inlet to the pump. Run the system. If the pressure at the inlet is not in the range of 10 psi to 15 psi cold, or 10 to 18 psi hot, find out why and fix it.

delay1968

Jamie Hall said:

There is an old saying which could be modified to apply: fool me once, shame on you. Fool me twice, shame on me. The modification here is -- you have had three (?) pumps fail. The odds of its being a pump problem, then are nearly zero. Do some of the piping changes suggested and get the expansion tank working properly -- it isn't -- and, just for safety, put a pressure gauge tap at the inlet to the pump. Run the system. If the pressure at the inlet is not in the range of 10 psi to 15 psi cold, or 10 to 18 psi hot, find out why and fix it.

Yes, I now agree that it is not the pump. I thought that was clear from the title of my original post.
There are now isolation valves on either side of the pump and these have drains. Could I hook up the gauge (need to get one) to the drain on the valve on the inlet side? I attached a newer pic that shows the valves (the drains are not visible but I imagine it is a pretty standard setup). Also included a stock pic of the valve type.

delay1968

At this point, I think it is most likely a combination of poor water quality and an issue with the expansion tank being made worse by a non-ideal setup.


I think I just need to get a plumber in here that specializes in hydronic systems. Unfortunately, I am going to have to find someone based on online reviews (which has not done me too well in the past). I am afraid of putting more money into this and still not getting to the root of the problem but I just don't have the time or know-how to implement all the ideas you guys have given me. I was hoping there might be a simpler fix (i.e. oh you need to change out this one valve and you're good) but clearly that is not the case.

I am guessing none of you are in Brooklyn, NY are you or know anyone to recommend?

Jamie Hall

Good heavens, man. At least four of the folks on the Wall in the contractor section are in Brooklyn, or service the area -- and I can vouch for all of them. Check the "find a contractor" tab above.

delay1968

Jamie Hall said:

Good heavens, man. At least four of the folks on the Wall in the contractor section are in Brooklyn, or service the area -- and I can vouch for all of them. Check the "find a contractor" tab above.

Sorry, haven't really poked around here much besides the forum. I am already in touch with someone on here. Hopefully, it will work out. Otherwise I will do that. Thanks.

GBart

This has been so entertaining to read.

HomerJSmith

Yes, you can put a pressure gauge on the bibb tap on the shut off valves. Use a bibb water pressure gauge that you can buy at Lowe's or Home Depot and replace the 150# gauge with a 30# gauge. Connect it to the side port and open the side port valve and read the pressure.

Since you haven't changed the location of the Xtank, take a pressure reading before you do, with the pump running and record the pressure and then change the tank location and do it again.

What would your results be?

By the way how are you regulating your boiler cold water feed? I think your fill pressure should equal your bladder tank pressure and the tank pressure equal the static pressure + 5 psi.

HomerJSmith

GBart, says, "This has been so entertaining to read. " Glad to hear it, satisfaction guaranteed, but. please don't be to hard to satisfy!

delay1968

OK, so I can't get anyone out here til next week and had some time this morning so I did a little more digging. Not moving any pipes/parts myself but I was able to check a few things.
I couldn't find a 30psi gauge locally (Lowes, HD, and 2 plumbing supplies were a no go) but I found a 100psi guage with a large dial. The cold static pressure on the input of the pump is showing 10-11 psi, assuming the cheap gauge is reasonably accurate.
I also took a look at the 2 failed Armstrong pumps I have. Both have metal pieces rattling in the bearing/coupler section (broken springs?) and show nearly identical wear to the impellor. Pics Below. If i stick my finger in and turn the impellor, it rubs and makes the loose pieces rattle. I am guessing is the Cavitation mentioned? Would dirty water be enough to cause that level of damage in a few weeks to a couple months?

hot_rod

Are you circulating water, or gravel in that pump?

Drain from a low spot on the boiler and see what comes out. A dirt separator might be a good addition.

Cavitation can be very destructive also, and it sounds a lot like gravel in the pump.

You could have both things going on.

Pump sizing needs to be checked and confirmed, proper operating conditions pressure and air and dirt free environment. be sure it never dead heads.

A trained troubleshooter ear can usually pinpoint cause of an usual sound in a pump.

delay1968

hot rod said:

Are you circulating water, or gravel in that pump?

Drain from a low spot on the boiler and see what comes out. A dirt separator might be a good addition.

Cavitation can be very destructive also, and it sounds a lot like gravel in the pump.

You could have both things going on.

Pump sizing needs to be checked and confirmed, proper operating conditions pressure and air and dirt free environment. be sure it never dead heads.

A trained troubleshooter ear can usually pinpoint cause of an usual sound in a pump.

Wow, that bad, huh. Those 2 pics are actually from 2 different pumps, each were only in the system for a short time before making the terrible sounds.

When I drained some water from the spout coming off the side of the boiler, the first tiny bit looked pretty rusty but then it looked cleaner as it came out. No obvious debris. Same thing when the pump was changed and we bled the radiators. In one spot the water looked a little black, in some others rusty, but always turned clear pretty quick.

hot_rod

The problem with heavy debris like in that pic is it is hard to move out of a system. Just opening a drain cock won't do it.

It takes a fluid velocity about 5 feet per second to move big or heavy particles from a piping circuit or boiler.

Often that takes a 2 hp or larger purge pump to get larger diameter pipe flowing at that velocity.

A power purge nay be needed if you suspect its is debris causing the damage.

A dirt separator will remove down to a 5 micron size particle and not restrict the flow to the pump. That might be a good option if a power purge is not possible..

Assuring the pump is not cavitating will be a bit more involved.

I prefer separators to Y strainers as Y strainers collect the crud in the flow path and instantly start reducing flow. separators drop then particles out to the bottom bowl.

HomerJSmith

Ya, it kinda looks like cavitation in your pump, which I don't see very often in small circulators.

I Find it incredulous that a plumbing supply house doesn't have a 1/4" NPT 30# gauge. What is the pressure at the input to the pump while the boiler is running? I suspect that the pressure is very low may even be negative pressure. This would be because the location of the Xtank. A higher pressure at the input to the pump would suppress gaseous cavitation. Temperature also plays a part. The lower the pressure the lower the boiling point of water. A higher temperature also increases molecular activity.

You might want to consider a Caleffi Dirt Mag on your sys return.