Problem with Grundfoss CH Pump

[JulianS]

I returned from a trip abroad to find the house cold, despite having left the programmer set to run the heating every day. The upstairs radiators were hot but the downstairs not & the pump was not running. I suspected the diverter valve (Honeywell V4037A) as I've had the motor inside go before but it turned out not to be that (I fitted a new control head).

If I select CH or HW the pump has 240v across the terminals (measured on the terminal block on the top of the pump) but the pump doesn't run. I've unscrewed the vent plug & the impeller seems free to turn. There's water in the FE tank in the loft.

The pump is a Selectric MkII & it's about 20 years old. My question is: what does the capacitor inside the terminal block do? Is it necessary for the pump to run, & if so is it a replaceable item? I'd obviously like to try changing that before shelling out for a whole new pump. Is there anything else I should check first? The control system is a standard Honeywell Sundial Y plan.

 

[gas4you]

I'd just put a new pump on, chances are even if it was the capacitor the rest is old and worn anyway.

 

[bengasman]

a whole new grundfos is about 60 quid, don't mess about with parts that are not meant to be changed

 

[JulianS]

Thanks for the prompt replies. Looks like a new pump then.

 

[Agile]

I think that most people with a 20 y.o. pump would just go and buy one!

If you suspect the capacitor then measure the capacitance value, its usually about 2.6 µF.

Tony

 

[JulianS]

Possibly they would, but why spend £60 on a pump which (from the FAQ) could be an 'all day job' when the problem might be a £2 item which I could change in 1 minute.

I also have shut-off valves either side which are of the type of which the FAQ says 'don't expect them to work'. So it's highly possible I'm going to to be spending much of the day draining & refilling the system, & also have to buy more inhibitor making the job even more expensive.

Still, it doesn't seem anyone here has heard of changing the capacitor, so it looks like I don't have much choice.

 

[nickso]

you can change the capacitor on a grundfos. i do it all the time to boilermates as it avoids a lengthy draindown/refill.

 

[JulianS]

you can change the capacitor on a grundfos. i do it all the time to boilermates as it avoids a lengthy draindown/refill.

Do you change them because the pump has stopped working or is there some other symptom/problem involved?

Can I ask where you get the replacement capacitors from?

 

[ollski]

you can change the capacitor on a grundfos. i do it all the time to boilermates as it avoids a lengthy draindown/refill.

Can I ask where you get the replacement capacitors from?

I'd hazard a guess it's out of a brand new pump.....am i close?

 

[nickso]

you can change the capacitor on a grundfos. i do it all the time to boilermates as it avoids a lengthy draindown/refill.

Can I ask where you get the replacement capacitors from?

I'd hazard a guess it's out of a brand new pump.....am i close?

lol, yes it was out of a new pump. i sometimes forget i have a van full of spares and it doesnt matter how many i use as its not my money im spending.

i suppose the capacitors must be available somewhere but i dont know where. as said by someone else, unless its difficult to change then a new pump is probably best.

 

[Trundles Tricks]

How outrageous.... a pump that has only lasted 20 years.



Buy a new one you cheapskate!

 

[JulianS]

How outrageous.... a pump that has only lasted 20 years.

Buy a new one you cheapskate!

I don't understand why you feel I should rush out & spend money on something that may be completely unnecessary. I've no idea if changing the capacitor would solve the problem or not but surely it's intelligent to explore the possibility rather than simply throw money at the problem. If the pump needs replacing then I'll happily do it, but I felt it was worth asking on here in case someone knew the answer. I assumed that was the point of these fora.

But I guess that's the difference between those who being paid & those who are doing the paying.

 

[Terrywookfit]

How outrageous.... a pump that has only lasted 20 years.

Buy a new one you cheapskate!

I don't understand why you feel I should rush out & spend money on something that may be completely unnecessary. I've no idea if changing the capacitor would solve the problem or not but surely it's intelligent to explore the possibility rather than simply throw money at the problem. If the pump needs replacing then I'll happily do it, but I felt it was worth asking on here in case someone knew the answer. I assumed that was the point of these fora.

But I guess that's the difference between those who being paid & those who are doing the paying.

Buy a multimeter with capacitance range and check it then >

If capacitor is ok then replace pump!

You will however have a shiny new multimeter to check your new pump with if it goes wrong!!

 

[Corgigrouch]

How outrageous.... a pump that has only lasted 20 years.

Buy a new one you cheapskate!

I don't understand why you feel I should rush out & spend money on something that may be completely unnecessary. I've no idea if changing the capacitor would solve the problem or not but surely it's intelligent to explore the possibility rather than simply throw money at the problem. If the pump needs replacing then I'll happily do it, but I felt it was worth asking on here in case someone knew the answer. I assumed that was the point of these fora.

But I guess that's the difference between those who being paid & those who are doing the paying.

With all due respect, you had the answer in the first reply.. If you chose to ignore it, then that is your business. We do this job every working day of our working lives and gave you the best solution to your problem.. The purpose of the capacitor is to assist the pump motor in starting whilst under load, so if the pump does not start after you have wazzed it over with a screwdriver through the inspection cap, then it is toast.. Alternatively ask your local plumb center for a capacitor for a Grundfoss pump..

 

[Soggy_weetabix]

for the love of god, just change your pump!

Pish easy.

Dave