CH Busted Pump ?

[Malc C]

Hi guys, long time no post

Murphys law being what it is, I know I should of left that slightly leaky radiator valve as it was bound to cause trouble... but... I meant well.

I drained the system down, replaced the offending olive and then re-filled the system. Then went round and vented all the rads to the point that no air was coming out. All seamed well until the heating kicked in this afternoon when the rad I replaced the olive on would not get warm. All other rads warned up without any problem, so I then commenced to bleed the rad above the pipes from the rad I had worked on ( the rad with the replaced olive in in the hall, with the front bedroom rad directly above).

Half an hour later I noticed that some of the other rads were cooling down as if the thermostat had turned the system off, so I upped the settings so it still called for heat.. it was at that point the system pipe work in the airing cupboard where the pump etc is made a couple of bangs and the vent pipe could be heard spluttering and I noticed that the pump wasn't running, but was too hot to touch.

I've tested the wiring to the pump and there is 240 volts between the live and neutrals so voltage is being supplied to the pump. I let the system cool down for an hour so the pump was just warm to the touch, thinking it might be some thermal shutdown thing in the pump that might be stopping it, but when I turned the system back on nothing happened but the pump got hot again... so its's off to screwfix in the morning for a replacement. Could the airlock of killed the pump ?

Malcolm

 

[Softus]

Sealed system, or open-vented?

 

[Malc C]

Hi,

Open vented - gravity fed.

 

[Softus]

Have you checked that there is enough water in the F&E cistern?

Have you checked that the pump spindle is turning?

 

[Malc C]

Yup, the system filled up fine, and there is plenty of water in the F/E tank. The pump doesn't run...

I've let the system get cold, went up and flicked the power switch to the system. Controller lights up, activated the three way valve, but pump just got hot (like too hot to actually hold) after a few mins so the power was turned off again.

 

[Softus]

Well, it does indeed seem that the pump is dead.

Something I don't understand is your reference to an air lock.

When did this air lock occur?

 

[Dick Puller]

As Softus has a limited knowledge, he has failed to point out that you can unscrew the large nut on the pump & see if the pump is spinning?? However, the pump may have a faulty capicitor, which are readily available from a fully qualified time-served Plumber & a lot cheaper than a new pump.

 

[Steve69the69Gas]

well I'm intrigued

 

[Softus]

he has failed to point out that you can unscrew the large nut on the pump & see if the pump is spinning

Nobody has "failed" to ask or point out anything.

The OP has already stated that the pump doesn't run.

However, the pump may have a faulty capicitor, which are readily available from a fully qualified time-served Plumber & a lot cheaper than a new pump.

Indeed so.

Would you like to take over from here, and explain to the OP how to test his "capicitor", and, if faulty, how to obtain and install a replacement?

Please make it clear to the OP how long the warranty on the capicitor will be.

 

[Steve69the69Gas]

well I'm intrigued

 

[Dick Puller]

No, no softarze, you can Google that just like every other thread you answer. Are you a CC/CCC by the way, as you have a very limited knowledge of the trade.

 

[Malc C]

The capacitor may indeed be cheap, but to have it fitted by a timed served, qualified up to the eyeballs plumber will cost a darn sight more than a new pump

To answer the questions:

As I stated in the original post I drained down the system to fix a slight leak on a radiator valve. Once done i opened up the stop cock to the F / E tank and added some more inhibitor. I then went round and vented each rad until water ran out without any sign of bubbles. The system then came on and all the rads apart from the one I had been working on got hot, so the pump was working fine for a while. I then continued to bleed the rads and shut some off in a bid to get rid of what I assume was an air lock. It was then that I heard air ban through the pipes and vent from the overflow to the F/E tank. It was at this point I noticed the pump was quiet, but hot to the touch.

There is voltage going to the pump.
The pump doesn't run at all, just gets hot
All other electrics work - 3 way valve and controller
Unscrewing the nut in the middle has no affect (other than to dribble water which shows water is present in the pipe)

Whilst I intend to replace the pump lock stock and barrel, I would be interested in finding out how to test the capacitor and why it could stop the pump from running. My knowledge of capacitors is that they are used to smooth DC or suppress noise.

 

[Dick Puller]

Well son, calling a recommended time-served Plumber to replace your pump could well save you money cause;
Here's what a Dafty DIY'er may end up having to do;
Try & I mean TRY to disconnect the pump valves, if they are ball type valves they will leak, so you'll need to replace them - so another drain down, oh and even more air locks, then there's the question of what pump setting the 'circulator' should be set at, do you know the full 'heat load' of your heating system & the requirement of the 'index' radiator??

As always said, Plumbing & Heating looks easy, until you have no heating for 4 days over Xmas & 'erindoors is giving you an ear full........................LOL!!!

 

[Malc C]

Dick, the system has been running fine since last November. I've changed this pump 5 years ago after the original pump installed in 2001 by so called professional plumbers went belly up. So I'm quite capable of closing off the valves either side of the pump and swapping them over.

I'm sure the original cowboys to no account of the items you mentioned in your post

Can you answer my question.. how do I test the capacitor and what function does it play in the running of the pump

 

[Dick Puller]

capacitor and what function does it play in the running of the pump..........Basically in laymans terms; on a circulator, it stores a little power to kick off the pump, when there's a 240V DC supply to the circulator.

Perhaps 'erindoors could get you this for your Xmas?? If you are not still fannying around with yer central heating & she's not blanking you.....................LOL!!!

http://www.amazon.co.uk/gp/aw/d.html?ie=UTF8&a=0764576607