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Thread: Dead central heating pump?

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    Jay
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    Dead central heating pump?

    Hi,

    I think my 12 year old central heating pump may be dead.

    Symptoms are...


    Heating will work for a while then start to gurgle at the boiler
    Boiler starts to hiss as if the water is not moving around the system
    Pipes start to bang near boiler and near the pump
    Central heating boiler cuts out.

    If I tap the pump I can hear a gurgle eventually the central heating will come back to life but start the same symptoms show again in 30 minutes or so.

    I had a plumber out to see it and he said the pump could have dirt in it that is stopping it running correctly, used the bleed valve to get the pump moving again, charged me £40 and left.

    Before I either pay a plumber or maybe tackle this myself do you guys think it is the pump at fault here or maybe an air lock of some kind?
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    Re: Dead central heating pump?

    if you tap the pump i doubt its an air bubble, as its not hard to change I would do it myself.

    oh and never use that plumber again, you got took for £40.

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    Re: Dead central heating pump?

    Quote Originally Posted by GoNz0 View Post
    if you tap the pump i doubt its an air bubble, as its not hard to change I would do it myself.

    oh and never use that plumber again, you got took for £40.
    Agreed, on the first, but it all depends on, first, the plumbing ability of Jay, and second, exactly what the situation is with the pump. I went through a similar experience with the mother-in-law's
    boiler a couple of weeks ago. It ended up with the pump being changed, but that design of pump was no longer available, and the replacement was slightly larger, and wouldn't fit in the monumentally daft tight space it had been originally installed in. It necessitated, in the end, removing about half the boiler to get to the blasted thing, and some pipework modification to relocate it. It took two British Gas engineers about three hours, plus two visits from their area manager, to 'consult'.

    Granted, this was at the nightmare end of pump replacements, and the pump was quite a bit older than 12 years. More like 32 years, in fact. But, it can happen.

    As for the £40 being a rip-off? Not necessarily. Most plumbers will charge a call-out fee. And on computer work, so do I. First, if I get called out, it can take 15-30 minutes to get there, and perhaps the same to get home, or to the next job. I won't go any further than that, because you can't reasonably charge for the time. Well, not on the domestic side, anyway.

    So .... £40 may well be a minimum charge covering attendance, and the first x minutes, say, half hour. As long as you're told that, up-front, fair enough. If I get to a job and it takes 2 minutes, I win. If it takes 29 minutes, I lose.

    As for banging the pump, getting it going and leaving, again, fair enough. That's exactly what BG did on one of the, IIRC, 7 visits it took to get my mum-in-law fully sorted. They'd had anither failure (heat exchanger replaced) and suspected that the drain, flush, refill cycle had dislodged some dirt that made the pump stick. Most times, duslodging it and getting the pump started again, will be the end of it. But sometimes, the pump needs changing.

    Thing is, if that plumber hadn't got it started and left, Jay could have ended up with a bill for £200 for parts and labour to chanfe a pump that, in fact, was fibe and jyst needed clearing. Some plumbers would take that option, because they make more from it.

    Seems to me that plumber made a percentage call, that 'dirt' was all it was. In which case, he's honest, because he didn't ramp up the costs when it may well not have been needed. I'd give him another go.

    As for you noises, Jay, it's hard to tell without being there, and I'm NOT a plumber. But it's similar to the mum-in-law. British Gas did suspect, at one poibt, dirt, and at another, airlock. Even gaving fitted the new pump, and bled the refilled system, it made strange hissing noises for a day or two, but there's some self-regulating contraption on the system and the hissing dissipated over a day or two. During the time it was doing it, there was no air build-up in radiators, you know, the dead section at the top where air gets in, yet the entire system "hissed" for a day or two, slowly decreasing.

    It seems to me, as a non-plumber, that dirt is possible, airlock is possible, and a kbackered pump is possible.

    This is, perhaps, a good time to suggest one of those heating system insurances, like BG Homecare. They aren't necessarily cheap, but the mum-in-law had 5 vusits from BG engineers, and two from the biiler manufacturer, called in by BG. That call-out to the boiler-maker apoarently cost BG about £200. And the pump, heat exchanger, boiler electronics and several ither bits all got replaced. I shudder to think what it would have cost privately, but with that Homecare package, it was all covered.

    I know it's a bit horse and stable door, but .... makes you think.

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    Re: Dead central heating pump?

    One of those things difficult to diagnose at long distance.

    You can usually hear the pump start up, and run, they are rarely silent, and you can usually hear water circulating. The symptoms you describe with the boiler cutting out on overheat (especially if it is after only a short time) is also consistent with poor flow - which could be caused by a failed pump.

    As for changing it.... if there installer had some foresight, there may be isolating valves on either side of the pump. They may be operated with a handle, or more likely a screwdriver. If that is the case, you can switch off the system, shut the valves and remove the pump with minimal mess. You may need a couple of large spinners. That might give you more information.

    If it is the pump, most domestic pumps tend to be the same size, but if you can get the same make and model, it should just go back in using the existing fittings.

    If you don't have isolating valves, you will need to partially drain the system so the water level is below the level of the pump - remove and replace in the same way.

    It isn't a difficult job, but if you have any doubts, get a plumber in - and get a couple of quotes first.

    If you can't get a pump the same size, you may have to do a bit of pipework - again, unless you are sure of your abilities, you might be better of getting a plumber.

    I am assuming you have a heating system that is not pressurised, and has a small header tank. If you have a pressurised heating system, you are in a different ballpark and a plumber will be the safest option.

    If the pump is integral to the boiler, you should get it changed professionally.

    Grunfoss are one of the more popular/common central heating pump mfrs, and you can get them at Screwfix and most plumbers merchants. Plumbers merchants may also sell other makes.
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    Re: Dead central heating pump?

    Good point about isolating valves. One part of what BG did to my mum-in-law's system was to curse about the lack of isolators, and as they had to strip down, to install them.

    The old pump was very old. Apparently, new ones are also a bit smarter, and the housing is a bit bigger, to house the electronics .... or so I was told. The biggest problem was the the pump had been put between the boiler and a wall. Imagine about a 6 inch gap between the side of the boiler (bolted in a way you can't remove it with removing the boiler first) and the wall. It's like working in a six inch gap between two walls, with the pump on the ground, 18 inches deep in the wall. Much dark muttering and mumbling was heard about that.

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    Re: Dead central heating pump?

    Its an old style system with a large tank in the loft, tank in the airing cupboard and the boiler in the kitchen. The pump is in the space under the tank in the airing cupboard and does have screw valves either side of the pump. The pump is a british gas multihead III but sadly due to the new regulations if I get a plumber I need to get the new style pump, if i t do it myself I can put the old style in

    I was looking at this one

    http://www.screwfix.com/p/wilo-smart...ing-pump/33590

    The only thing I am worried about is the isolating valves not holding.
    Last edited by Jay; 14-12-2013 at 04:19 PM.
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    Re: Dead central heating pump?

    the valves will hold enough, put something under to catch drips.

    Capitalization is the difference between helping your Uncle Jack
    off a horse and helping your uncle jack off a horse.

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    Re: Dead central heating pump?

    The isolating valves are usually ball valves, so they should hold OK. Ball valves can leak a little bit (they aren't as secure as gate valves, but if the pump is in an upstairs airing cupboard, the pressure won't be that much. If you are worried, you can partially drain the system so the header tank is empty. If the upstairs radiators have valves at both ends, shut both of those first so the radiators don't drain. If they haven't, you'll need to bleed those afterwards and maybe add a some corrosion inhibitor as you will be diluting any that is in the system.

    However, I think that is likely to be unnecessary. If the pump is a direct replacement, it will only take a few minutes to actually remove and replace, so any seepage won't amount to much. Have plenty of cloths ready though because there will be water in the pump itself, and that will splash out.

    I can't comment on the suitability or otherwise of the pump. It isn't one I have used, but it has good reviews, and if the distance between ports is the same as the one you are replacing, it looks good value for money.
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