hot radiators, lukewarm water

Pumps have two pipes, an inlet and an outlet!

Would you like to take a photo and post it here?

Tony
 
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You can get a grundfos pump plan as this
http://www.plumbnation.co.uk/site/grundfos-upp15-50-pumpplan-twin-headed-domestic-circulator-pump/
You would need to alter the pipes slightly to change it or you could alter it to an S or Y plan

Smc pumps were very reliable. About the only thing that failed was the capacitors. Don't know if replacements are still availaible though.
The motors did not burn out very often as the impeller is not turned directly by it, but by magnetic action so if the pump jammed the motors didn't burn out.
That is why they have a bit less power than the modern ones as they are not directly driven.
It didn't take much to stop them turning. so it is possibly just sticking. Tap it with a hammer and see if it starts or strip it out and check the impeller turns freely.
It could also be a faulty relay.
Have a read of this
http://www.horstmann.co.uk/downloads/ElectronicDocuments/Packs/SMCReplacement2.PDF
The existing relay is built into the timer. You would have to replace the timer and add a relay as the above.
The new relay needed would be a 240v single pole change-over (SPCO).


Tony it is an SMC Controller system with 2 pumps.
 
Hi Tony, thanks for still following the thread.

Pumps have two pipes, an inlet and an outlet!

Would you like to take a photo and post it here?

Tony

Apparently, not all pumps. Mine is exactly like the "SMC Controller" here (already posted) http://www.gasman.fsbusiness.co.uk/fully_pumped_systems.htm. Three pipes: one from the boiler, one to the hot water tank, and one to the heating pump. And because it is so different from usual systems, it is so difficult to find a replacement...
 
You can get a grundfos pump plan as this
http://www.plumbnation.co.uk/site/grundfos-upp15-50-pumpplan-twin-headed-domestic-circulator-pump/
...
Have a read of this
http://www.horstmann.co.uk/downloads/ElectronicDocuments/Packs/SMCReplacement2.PDF[/QUOTE]

thanks tamz, very interesting info. That pump sure isn't cheap! Ignorant's question: would it be possible to just substitute the 3-way HW pump with a standard 2-pipe one placed on the pipe to the tank, plus a bypass to bring water directly to the CH pump? Essentially the pipe from the boiler splits in two and feeds 2 separate circuits, each with a standard (2-pipe) pump, one controlled by the room thermostat, the other by the cylinder thermostat.
 
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That pink shows several systems and one shows the SMC controller pump as well an ordinary pump.

I have only once seen one of those when I was taking out an old system.

As I recall its only a motorised valve in a casing a bit like a pump.

Thats of no consequence because any of those bits can be replaced with current parts.

You probably need a new pump as well as a three port valve and some rewiring. Not a very big problem. I am surprised that your plumber could not see what was needed. Or perhaps he thought that you did not want to pay for whats needed?

A new pump and valve installed would probably be about £230-£330 depending on how much is charged and what quality of pump is fitted. The parts could come to £80-£140 depending on the brands chosen.

Few heating repairs are less than £84 and the average car repair is over £240 for the cheapest to repair and about £800 for an average repair on a Saab.

Tony
 
You probably need a new pump as well as a three port valve and some rewiring. Not a very big problem. I am surprised that your plumber could not see what was needed. Or perhaps he thought that you did not want to pay for whats needed?

Oh no, I'd pay whatever is reasonable. I think my plumber was more interested in selling me a completely new boiler though, he didn't seem keen on doing any "minor" work.
If I could find someone I can trust in Cambridge, I'd happily pay to fix the damn system, but I certainly don't want to be taken for a ride...

So I guess this is now also a call for a honest, expert plumber willing to modify an old broken SMC system... any takers?
 
Smc pumps were very reliable.
...
It didn't take much to stop them turning. so it is possibly just sticking. Tap it with a hammer and see if it starts or strip it out and check the impeller turns freely.

hi tamz, I tried tapping the pump gently but still no life signs. Is it possible to open it up partially leaving it connected to the pipes, to check the motor and clean it? I need just a little help, I don't want to untighten the wrong screw and flood the house.
 
As far as I recall those pumps cannot be spun like the current types.

If the system is drained then they can be taken apart and cleaned.

However, the problem seems to be your motorised valve and not the pump.

Tony
 
The SMC Controller was a pump, not a valve, and it did have three pipes.

You can't spin the impellor on SMC pumps.

I would advise you to get it converted to a Y Plan layout - unless you are intending a boiler change anytime soon - in which case go for a good System boiler with built in pump and diverter valve, or a heat only boiler with a new pump and Y Plan - and weather compensation for the thinking man.

Continue with the immersion for a brief while if you plan to have a new boiler soon.
 
I would advise you to get it converted to a Y Plan layout - unless you are intending a boiler change anytime soon - in which case go for a good System boiler with built in pump and diverter valve, or a heat only boiler with a new pump and Y Plan - and weather compensation for the thinking man.

Continue with the immersion for a brief while if you plan to have a new boiler soon.

That has already been suggested by someone out of this forum, and is probably what I'm going to do.
Actually, I'm thinking S-plan, because the cable to the cylinder thermostat has only 2 cores+earth and it can't be replaced easily (embedded into the wall and under floorboards).

Still, if there were a way to fix the SMC pump, without changing any pipework, I'd go for that. Anyone has any experience with it, things that I could try?
 
For anyone interested, it's all fixed now. I converted it to S-plan, not Y because I only have a 2-core wire going up to the hot water tank. It was a very interesting project, all done by myself, with help via email from the extra-nice and knowledgeable guy who has this website: http://www.gasman.fsbusiness.co.uk. Gasman, thank you!

Anyone interested in an SMC controller? Broken but who knows, maybe easy to fix. :)
 
For anyone interested, it's all fixed now. I converted it to S-plan, not Y because I only have a 2-core wire going up to the hot water tank.

That did not need to be any limitation because a two wire could have operated a relay to initiate a change over contact.

Tony
 

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