Life span of a circ pump

[hdshinn]

What's the best guess for the life span of a circ pump in an in-floor hydronic heating system? Pretty broad question I realize but my boiler/system maintenance contractor has diagnosed a pump problem in one zone of our system. The system is about 10 years old.

Buderus boiler & indirect domestic hot water. One zone feeds upstairs baseboard radiators, the other the lower in-floor radiant. The problem is I don't seem to be getting very hot water to the manifold for the floor zone all the time. The manifold is warm to the touch most of the time and only occasionally is it at or above say 120 degrees even when all the t-stats are calling for heat and the zone valves are completely open. The baseboard zone is almost always up to temp so long as one or more t-stats are calling for heat.

The behavior seems more something that would be caused by a malfunctioning mixing valve. Is it possible for a pump to only circulate part time even though it's running full time?

The boiler temperature is set for 190 degrees but I've not seen the actual water temp above 145-150.

Life was a lot simpler when all we had to do was set fire to a pile of logs.

 

[Gary S]

They last until they die. The original one in my hot water system in my house lasted 55 years before the bearings got noisy. I don't expect the replacement to last even 1/2 that long. Things today aren't built to last like they were in the 50s.

 

[Highbeam]

"Life was a lot simpler when all we had to do was set fire to a pile of logs."

A growing number of us still do. I heat 100% with wood in the house.

 

[custom1]

"Is it possible for a pump to only circulate part time even though it's running full time?"

I don't know what kind of pump you have or how it's constructed, but I have seen the impeller become loose on the shaft in other kinds of pumps(sump pumps etc), so it would be possible for the pump to be running but not moving fluid.
Is your system constructed so the pump can easily be removed?

 

[hdshinn]

...Is your system constructed so the pump can easily be removed?

It's removable but not easy. Meaning the ding-dong installed it really close to the wall between two other pipes so it's gonna be a ****** getting a wrench on the two bolts behind the flange on either side. Yes, it's designed to be easily replaceable but it was installed in a way that made every effort to defeat the process.

It's a Taco hydronic heating circulating pump for what that's worth.

 

[FXDawg]

Have you had any parts replaced recently. Could need a purge. However, if your aquastat is set to 190 and you are only getting 140 to 150, there is another problem. If a zone valve is stuck open and only one pump supplies the water to all zones, and your pump continually runs, you may be sending heating water through that zone constantly. depending on what that zone is, you should feel the difference in an over heated space or really hot water on you domestic HW system.

However, the low temp is really concerning me. Is you boiler constantly running to try and keep up? Have you added another zone by chance? It could be that the boiler isn't big enough to handle the load you have on it. It could be your aquastat needs replacing as it isn't getting you up to temp or, more accurately, giving a false reading and turning the boiler off at the wrong temp.

So, if the boiler is not constantly running, trying to get up to temp, it seems, it might believe it is up to temp because of a faulty control and cutting off prematurely. If, on the other hand, it is constantly running and unable to reach the temp it is set for, and you are not seeing an over heating situation somewhere, I'm back to thinking it may be an undersized boiler. Because, if you had a stuck zone valve sending heat to that zone every time the pump ran that zone would be getting more heat than it needs. If the pump is constantly running because one or more zone is never satisfied, the boiler is not able to make enough heat to satisfy the load. if you have not added any more load to the boiler then maybe you need a tune up or something else if effecting the boiler's efficiency.

 

[FXDawg]

It's removable but not easy. Meaning the ding-dong installed it really close to the wall between two other pipes so it's gonna be a ****** getting a wrench on the two bolts behind the flange on either side. Yes, it's designed to be easily replaceable but it was installed in a way that made every effort to defeat the process.

It's a Taco hydronic heating circulating pump for what that's worth.

oh, those pumps are nearly impossible to detect whether they're running or not... They are so quiet. And the do go bad. it isn't a bad idea to have a spare. especially if it is doing all your work and supplying all the zones. Some people install (me included) a pump for every zone. This help with wear and tear and the pump generally last longer.

I'm still worried about you boiler not coming up to temp...

 

[FXDawg]

Does the boiler have an outside air temp probe that adjusts the boiler to outside air fluctuations? Is it a warm day there?

 

[hdshinn]

FXDawg;

Wow, what a great response. Thanks!

OK -

Have you had any parts replaced recently. Could need a purge.

No, nothing's been altered since the system was installed. Other than to separate out the kitchen floor circuit that had been on the same 'stat as the living room. But this was a wiring/control mod, nothing to do with the piping so the system wasn't open, or shouldn't have needed to be. In addition I should think the automatic air vent would take care of any possible air lock.

, if your aquastat is set to 190 and you are only getting 140 to 150, there is another problem

That's my problem - there are too many things that seem to be going on that I simply don't understand. Everyone that's looked at this system assures me that it's been sized correctly for the house. I'm leaning in favor of your advice on the aquastat. The boiler does not run constantly. And there are two pumps, one for the baseboard heating on one zone and the other is for the in-floor radiant. A third one is for the domestic hot water. How would one go about testing the aquastat hypothesis? It's probably not something for a home owner to attempt(?).

The floor zone pump seems to be running constantly which I've determined by feeling the vibration plus the motor is quite warm to the touch. That said, how can a pump not be working part of the time and working at others? The maintenance guy shut off the isolation valve at the outlet side of the pump which usually, according to him, would result in an audible sound as the water flow was being restricted. There was no sound of rushing water. That's where he came up with the bad pump diagnosis.

, if you had a stuck zone valve

All the zone valves are working; they're open when their respective 'stats are calling for heat and close when they're not.

Does the boiler have an outside air temp probe

Yes. But you got me thinking I should check to make sure it's not been obscured with spider webs of hornets from last summer.

At the risk of going to the well more often than I should, would it help to post some photos of the piping, manifold, etc., to provide a better "picture" of the system?

Thanks so much for the response. I'll give the aquastat question some attention.

 

[Highbeam]

We all love pictures. Even if for nothing other than to see another mousetrap.

 

[FXDawg]

FXDawg;

Wow, what a great response. Thanks!

OK -

Have you had any parts replaced recently. Could need a purge.

No, nothing's been altered since the system was installed. Other than to separate out the kitchen floor circuit that had been on the same 'stat as the living room. But this was a wiring/control mod, nothing to do with the piping so the system wasn't open, or shouldn't have needed to be. In addition I should think the automatic air vent would take care of any possible air lock.

[FX] Not really, if the air pocket is out in the house somewhere it will take forever to get to the boiler and vent through the scoop and out the auto vent

, if your aquastat is set to 190 and you are only getting 140 to 150, there is another problem

That's my problem - there are too many things that seem to be going on that I simply don't understand. Everyone that's looked at this system assures me that it's been sized correctly for the house. I'm leaning in favor of your advice on the aquastat. The boiler does not run constantly. And there are two pumps, one for the baseboard heating on one zone and the other is for the in-floor radiant. A third one is for the domestic hot water. How would one go about testing the aquastat hypothesis? It's probably not something for a home owner to attempt(?).

[FX]Try turning the dial up to like 210 and see if the burner kicks on and starts to bring the boiler temp up.

The floor zone pump seems to be running constantly which I've determined by feeling the vibration plus the motor is quite warm to the touch. That said, how can a pump not be working part of the time and working at others? The maintenance guy shut off the isolation valve at the outlet side of the pump which usually, according to him, would result in an audible sound as the water flow was being restricted. There was no sound of rushing water. That's where he came up with the bad pump diagnosis.

[FX]well, there is a lot of mass under that floor between the concrete and the earth if it is a slab. that could be why it is running and running and never gets up to temp. That could also make it difficult to satisfy because of the cool boiler. However, radiant floors usually don't require that 180 degree water. 110 is usually sufficient.

I'm not so sure about that whole closing the valve and listening, the boiler only runs at about 12 lbs and you'd only hear it if there was some air in there as well. works on domestic water because you have a lot higher pressure.

, if you had a stuck zone valve

All the zone valves are working; they're open when their respective 'stats are calling for heat and close when they're not.

Does the boiler have an outside air temp probe

Yes. But you got me thinking I should check to make sure it's not been obscured with spider webs of hornets from last summer.

At the risk of going to the well more often than I should, would it help to post some photos of the piping, manifold, etc., to provide a better "picture" of the system?

[FX] what is that saying about pictures and words?? LOL sure post some pics. Pics of the dog, car, motorcycle and your wife or GF are always appreciated too!! JK LOL

Thanks so much for the response. I'll give the aquastat question some attention.

You're very welcome! I'd try turning the dial up on the aquastat and hang around and watch to see what happens. Could be the probe got moved away somehow. Sometimes they just strap then to the pipe. It should be in a well.

Keep us posted!

Danny

 

[Mabus77]

Do you have any check valves or flow control valves on the system ? Usually they are installed on a single boiler multi zone system. It prevents the hot water from circulating while the pump for that zone is off but another pump is on. Here's a picture of one :

 

[Rickcnc]

What's the best guess for the life span of a circ pump in an in-floor hydronic heating system? Pretty broad question I realize but my boiler/system maintenance contractor has diagnosed a pump problem in one zone of our system. The system is about 10 years old.

Not sure about a circ pump for in-floor but my Ground source circ pump lasted 5 years 2 months (it's amazing how it managed to hang in for 60 days past the five year warranty)

 

[hdshinn]

Mabus: No check or flow control valves that I can make out. Don't mean there isn't one.

FX: I bumped the aquastat dial up to the full 190 deg setting without noticing any appreciable difference. What's puzzling is that all the rooms on the lower floor (with the in-floor heating) come up to temperature as set on the 'stats but never above. The 'stats keep calling for heat, the zone valves are open and the manifold is just warm to the touch. The output of the pump in question has a thermometer well & thermometer which reads on average about 90 degrees. I'm aware that the baseboard side of the system requires hotter water than the in-floor. The baseboard supply thermometer on the pump for that side reads pretty consistently at 130-140 degrees.

I've got a local hydronic heating guy coming out that has a lot of experience with these Buderus boilers and control units so I'm hoping he can debug it. Over the phone he expressed his dislike for the Loganomatic controllers and that they tend to get 'confused' when there's a lot of odd things going on with the outside temps. Which has been the case here in Western WA this winter. There may indeed be nothing wrong save for my ever persistent paranoia.

If or when I get an answer, if there is one, I'll keep ya posted.

Rick: If I had a dollar for everything that went toes up a month or so after its warranty I'd move to a warmer climate! (haha)

Thanks, everyone!

 

[Sureshot]

You may not have to undo the flanges. Can you undo just the top section? Likely allen screws. Reuse the "base" or housing.

 

[hdshinn]

OK - had another heating guy go over my system and ...

Pump is fine. He pulled the cartridge out, fired up the unit and everything spun up as it should. So -

After about an hour & 1/2 he discovered the actuator on the mixing valve had been connected backwards. In other words, when the boiler controller was telling it to open it was actually closing. We had been getting a moderate amount of heating water through since, as it was explained to me at any rate, the mixing valve never really closes completely. Plus there was a little back feed from the baseboard heating circuit as well.

End result is this morning all the stats were up to temperature, the mix water going to the in-floor circuit was being modulated correctly and the whole system appears, at least for the moment, to be functioning as it should.

An hour & 1/2's time for two mechanics wasn't exactly cheap but it was a lot less than parts & labor to replace that circulator!

Once again I thank all the folks here on the forum for their replies and especially FXDawg for his insight. For the time being, anyway, I think we've got the problem put to bed.

[edit] Also, FX, I meant to add that the in-floor is an elevated 2x10 framed structure, 3/4 plywood and 1 1/2" fiberglas reinforced regular wt concrete placed with a high range water reducing plasticiser(sp) additive. Underfloor insullation is 10" unfaced fiberglas between floor joists. (just to complete the picture)

 

[hdshinn]

You may not have to undo the flanges. Can you undo just the top section? Likely allen screws. Reuse the "base" or housing.

Yeah, Sureshot - I wasn't familiar with how those things go together and come apart. Four cap screws hold the cartridge to the base housing. We removed the cartridge, turned on the boiler and the pump motor and rotor spun up fine. No bearing noise, no binding, blah-blah.

Learned a lot during this episode. The most important being, avoid installing the Loganomatic controller for your hot water heating system boiler. Way to complex.

 

[custom1]

After about an hour & 1/2 he discovered the actuator on the mixing valve had been connected backwards.

So has it been that way for 10 years, or was this caused by someone working on it recently?

 

[hdshinn]

The actuator was "replaced" a couple years ago, come to think of it, to presumably correct a similar behavior problem at that time. So in essence I suspect it never has performed correctly. Any wonder why my propane bill has been so high.

 

[BadgerBoilerMN]

You want to keep a good relationship with the guy that fixed the current problem.

We are factory trained to service the Buderus GB142 condensing boiler and perform annual maintenance (factory mandated) for lots of people here in Minneapolis. Your factory trained technician should be cleaning the heat exchanger, checking the flame sensor signal, testing pH of the water, cleaning the condensate trap, etc. etc. every year towards the end of each heating season.

 

[hdshinn]

BadgerB -

Yep, we have the boiler serviced every year but usually at the beginning, not the end of the heating season. Thanks for the tip on water pH and condensate trap. Not sure if this is part of his routine. I'll request it next time.