NO HW NO CH, Honeywell diverter valve

Sounds like a duff pump to me. If the pump is consuming electricity but not revolving it will get hot - from electrical energy dissipated in it.

If the pump is not pumping, little or no water will circulate. The pipes may get slightly warm due to conduction and natural convection.

If the water heated by the boiler cannot go anywhere, the boiler will either stop firing when its stat opens (if you're lucky) or will more likely overheat so that its safety cutout trips. Does the boiler still fire?

If I am right, replacing the pump and, if necessary, re-setting the overheat trip on the boiler should fix your problem.

Roger

Roger,

I am coming to your way of thinking that is it the pump. When I listen carefully to the pump it make a faint grinding noise - when the CH timer is "ON". When the timer is "OFF" - no grinding noise from the pump. When I say "grinding" the noise is very faint, not even as loud as the familar "whoosh" and "whir" of an operational pump. This pump is only 2 years old !!!

Now, I have been told you can take the pump bit off and leave the plumbing bit in - by undoing the four Allen bolts attaching the electric pump housing to the "rest".

How do I know it is the "electrical pump" that is the problem rather than the "vanes" that are in line in the water flow?

The model is a Potterton Myson Celsia (I didn't note the exact model)

I have searched and searched on the net for spares for this model and can't find them anywhere.

If I buy the new pump , will it come with the "vanes" that sit in the water flow. It is possible on this installation to isolate the whole pump and replace it as the installer put an isolation valve both above and below the pump. However, I want to avoid removing the whole lot if at all possible

Thanks,

Clive

My guess is that it is probably the mechanical bit which has partially seized - because the electrical bit is still consuming power, and may be ok - except that overheating won't have done it any good.

Far safer to replace the lot. If, as you say, there is an isolation valve either side, it should be easy enough to replace it without draining the system.

Roger

Its very common at this time of year for pumps to be found locked by crud due to not being used over the summer. Have you tried freeing the pump by turning the shaft with a screwdriver? There is usualy a cover in the middle of the round end that you take off with a coin to get to the screwdriver slot.

If the pump is u/s its standard practice to change the whole pump. That why the isolating valves are there. The shed all have pumps, get one with the same or higher head rating. Virtually all replacement pumps should fit but trying to get bits of a new pump to fit into old pump body would be fun to watch :-)

Hi,

I did wonder if the pump is "stuck" rather than "stuffed" . At the end of the pump head is a black plastic hexagonal nut. This just sits on top of a smaller hexaganol brass nut. No "slotted" screw head to enable me to try to "hand crank" the pump. I am going to take the hexagonal nut off and see what is underneath. It might leak - who knows? There is NO technical info for this pump anywhere on the Net. The model number on the body is IP41.

By the way I found out the company that makes these pumps underwent a Management Buy-out. They are now called CIRCULATING PUMPS and are still located in their Kings Lynn Norfolk premises

The supplier of this pump in North London is Fountain Thomson Moore

- so I might be there at 8am tomorrow. Why couldn't the plumber have fitted a Grundfos? Everyone stocks those.

Clive

Final story

I was the pump wot did it

The original "pump inlet" was completely bunged up with what is politely called detritus

Taking the old pump head off and fitting the new one - say 60 minutes

- I had never done one before. Made much, much easier (in fact could not have done the job other wise) was the presence of the two isolating valves around the pump body.

No leaks from the pump - hot water cylinder heated up in a couple of hours - rads slowly getting warmer.

A real plumber suggested I flush with Sentinel 400 and then finish off with Sentinel 100 - I will do that in a couple of weeks. However, if there are lots of bits of rust floating around in the system - I don't give the new pump much longer than the 3 years the other one lasted

All the materials - £63 inc. VAT. My time overall - 4 hours plus thinking time.

Thanks to PMT, Russell Lane, London N20 for all the help and advice. I recommend them.

Clive