ufh problem

[skivest69]

i am trying to connect a new underfloor heating system to an existing s plan system. The problem ive got is it is a very old boiler with only a switched live so when ufh is asking for heat the heating/hot water pump runs aswell as it is connected to boiler switched live.How do i remedy this as plumber says it will burn the pump out.

 

[telectrix]

plumber is talking cobblers. i had a similar install the other week. ask geordie.

 

[skivest69]

i only have a limited plumbing knowledge so finding it hard to argue .he says existing system doesnt have anywhere for pump to pump the water if hot water and heating are both off but hot water/heating pump is running because ufh is calling for heat

 

[telectrix]

i know little about plumbing as well, but i was assured by the plumber on my job that the pump would be OK. it's been running now for a month with no probs. geordie is your man for confirmation here. the boiler pump will pump to your ufh pump and so it does have somewhere to pump to.

 

[chalky]

Forgive me if i am wrong but wont the original pump pull the water to the ufh manifold then the underfloor heating pump will pull the water round the underfloor system when relay has opened on the ufh control box.

 

[telectrix]

that was my thoughts. as usual, plumbers talk through their arses. must be all that sewage in their pants.

 

[Deleted member 9648]

i am trying to connect a new underfloor heating system to an existing s plan system. The problem ive got is it is a very old boiler with only a switched live so when ufh is asking for heat the heating/hot water pump runs aswell as it is connected to boiler switched live.How do i remedy this as plumber says it will burn the pump out.

Use 2 relays. One energised by the heating/HW boiler trigger,the other by the UFH boiler trigger. Pemanant live linked across the common of the two relays.....Switch wire to boiler linked across the N/O contacts of the two relays.

 

[skivest69]

thats what i thought

 

[skivest69]

i was thinking relays but dont use them very often so was a bit lost with the wiring. cheers i can fully understand that now

 

[jackhammerJIM]

a separate zone for the underfloor would have been nice

 

[ste mac]

Plumber is talking out of his waste pipe. The idea of the UFH manifold having a pump is just to boost flow around the UFH heating pipe work (long run of narrow pipe with lots of bends) and to assist the original CH/DHW pump. I have wired several wet UFH systems & they all have two pumps running together without a problem.

As per this diagram http://www.ukunderfloorheating.co.uk/index.php/download_file/-/view/290/

 

[longboat]

i am trying to connect a new underfloor heating system to an existing s plan system. The problem ive got is it is a very old boiler with only a switched live so when ufh is asking for heat the heating/hot water pump runs aswell as it is connected to boiler switched live.How do i remedy this as plumber says it will burn the pump out.

You need to use a double pole relay. The plumber is right, it's not ideal to have the main pump running when only the underfloor heating is calling.
Did one a couple of years back but can't remember the wiring diagram.
Will see if i can find it and add a link.

Not double pole, but anyway this should help.http://www.gasman.fsbusiness.co.uk/images/SMC Twin Pump.bmp

 

[guest119]

Is there not a radiator somewhere in the system that is fitted with 2 lockshield valves (permanently open)?

Boydy

 

[PEG]

The pump running too much could be inefficient and wasteful,but if not out of heat range,it will not burn out. I fitted an old Grundfoss unit to recirculate a pond filter flow 12 years ago,and it has run non-stop eversince...they are one of the toughest items in any house :sorcerer:

 

[electric will]

Deleted, been drinking probably wrong.