Central Heating Failed

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Take a look at your expansion tank and check the water colour.
Your system needs cleaning, but the cause of that bright orange deposit needs investigation. It indicates highly oxygenated water. You may have a blocked cold feed.

Expansion tank water seems quite clear.

Follow the pipe down from the F&E (expansion) tank to where it tees in to the system. At this point see if you can feel any pull on a magnet. If there is magnetism it may be very slight.
If there is magnetism here this indicated that the cold feed into the sytem is blocked.
You could compare placing the magnet on a copper pipe to a tap to see how a clear pipe should feel!
 
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You won'y get scalded and if you want to inspect the impeller you can switch everything off, undo the allen keys and pull it apart .

You can see the impeller in the second photo. Looks dirty but otherwise ok. In any case what/where ever the cause of this blockage just change the pump.
 

MTK

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You won'y get scalded and if you want to inspect the impeller you can switch everything off, undo the allen keys and pull it apart .

I manually set the diverter valve to 'MAN OPEN'. I powered the system back-on (the 'gas-fired water heating device' fired up) and I unscrewed the seep-cap. The CIRCULATOR spindle wasn't rotating!!! I manually rotated the spindle with a screwdriver (fortunately in the correct direction) and the motor fired into life!

I now have tepid heating (presumably it is simultaneously heating the water tank too).

Oddly enough, I had applied a 'percussive adjustment' to the motor at the very beginning but it made no difference.

Now I didn't expect the motor to run for very long but I had forgotten to turn the system thermostat back-up so after half a degree improvement the system shut-down. I dashed out to turn the thermostat up, the 'gas-fired water heating device' fired up immediately and guess what...the 'circulator' motor was still again. Once more I removed the seep-cap (this time I got a much more direct squirt of water than I was expecting!) and I 'kick' started the motor. Hey Presto! Central Heating again.

I shall have to turn the system off completely tonight because the circulatory device obviously can't manage entirely on its own.

Firstly, many thanks again for all your help so far.

Secondly, given this update I would be most grateful as to what you now think I should do;
(a) in the morning to get my immediate-needs heating back, and
(b) in the shorter term to maintain the entire system.
 
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Secondly, given this update I would be most grateful as to what you now think I should do;
(a) in the morning to get my immediate-needs heating back, and
(b) in the shorter term to maintain the entire system.

I told you this 2 posts ago...
 
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CBF

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FFS it's simple as Breesey told you :rolleyes:

the pump is knackered replace it

the system needs a chemical flush either a powerflush or a manual one

the cold feed may or not be blocked, drain some water out of the system does the f&e tank start filling ? yes the c/f isn't blocked, no then it's blocked
 

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Thanks for all the replies and kind help.

Sorry if I I'm being a bit slow about what to do.

I shall endeavour to replace the pump today and then investigate system cleansing.

BTW, when I depress the ballcock in the header cistern water feeds into the cistern as expected.

Would it make any sense for me to replace the (original) pump with anything other than a near identical match?

Also my existing pump is a 'Grundfos 15-50 x18'. What do each of those numbers mean please?

I have seen 'Grundfos 15-60 Domestic Circulating Pump' listed but I haven't found one in stock locally yet - although I think this may be a reasonable match.

Alternatively I think I could obtain a 'Grundfos Alpha 2L 15-50' - would an auto-sensing pump be of benefit in my 1989 system?
 
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Your pump sounds like its running ok but you need to change the capacitor, BTW its no good pushing the ballcock, you need to drain some water out of the system and then see if the ballcock refills the tank.
 

MTK

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Oh crikey! So I may not need to replace the motor but just the capacitor?

Other than removing the whole pump (to get access to the electrical connections panel and thence the capacitor), is there any way to find out
(a) exactly what capacitor I need, and
(b) where I can obtain one quickly?

For clarity, when the system is fired-up the motor always requires me to manually twist its spindle in order to get it running. Is that purely symptomatic of a failed capacitor?
 
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That model pump is not made anymore so you will have to change it.
Alpha2/15-50 or a selectric 15-50 will do you or there will be one on ebay the same as yours.
You may need spacers with the above new pumps but these are available off the shelf.
I would not put a new one on that system until cleaned/sorted.
 
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It may be worth putting some 'Sentinel X400' in the system to begin with, follow the instructions on the bottle for correct dosing. This is a chemical cleaner than can be safely left in the system for extended periods, and should help to loosen up some of the rubbish in the system. (Do not use the X800, this is only suitable for use with powerflushing machines.)

Once this has had chance to take effect then drain and refill the system, might be wise to do this daily for 2-3 days, (run system as normal once you've refilled and bled it each time) to remove as much crud as you can. On the final refill add some inhibitor, which neutralises the water and prevents further build up of sludge.

However, if system is overpumping (pump is pushing water up the vent pipe into the F&E cistern rather than around the system) then the cause needs addressing or you'll be looking at early failure of key components in the system.
 

MTK

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Once again, thank-you for all the kind and helpful replies.

As onecog kindly confirmed, the exact model I had (original) is obsolete now. I suppose that's the risk when being so kind to kit that is kept for 24 years (when the original warranty is usually 1-2 years).

I was having difficulty sourcing a near-identical pump in stock locally.

Meanwhile, I had a near-identical pump in an otherwise identical heating system in my garage/annex and since I don't actually need gas central heating in there anymore I have swapped that pump into the main house system. I've just fired it all up and it seems to be running nice and sweetly...

I'll need to drain the garage/annex system before any further hard frosts but that's OK.

If the swapped pump (continues to) work fine for now in the house then maybe I'll reconsider a new pump when the whole main house system has been cleansed (which I'll hopefully plan in the next few weeks when the ambient temperature isn't quite as cold as now).

I'll aim to either do a powerflush or have someone in to do it (eighteen radiators in the main house system).
 
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You still very likeley have a blockage on the feed pipe. You need to confirm that you haven't. The system needs draining and cleaning generally as well or you will be chamging the pump again soon.

Of course taking any advice is entirely up to you... :rolleyes:
 
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As others have said, the system defo needs cleaning! From the sound of it the old pump might have sheared the shaft/spindle (have had a number of these pumps go that way) but if you've swapped them over you could try stripping it down and checking. Trouble with just checking the spindle through the screw cap is it doesn't tell you if the impeller is still attached! (unless you have gauges either side of the pump). Having to start the pump with a screwdriver is down to the crap in the system causing the impeller to stick and not enough ooomph in the motor to get it going.
Dose it up with system cleaner and flush through, then a good inhibitor.
 
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PUMP is probably the most wrongly used term in a heating circuit it is a circulator not a pump, it can circulate it cant prime or PUMP water and as such being restricted like yours is it cant do its job it circulates water not rusty mud

The full name for this type of pump is a circulator pump. So still a pump whichever way you look at it.
 

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