U/F heating costing a fortune!

[rainstorm]

Hi All,

I've been asked to look at an underfloor heating system that is obviously wired up wrong.

The property has 2 combi boilers, 1 of which is solely for the u/f heating.

The ground floor has 2 manifolds, 2 pumps (located together) and 6 programmable stats, 1 for each room/area.

Upstairs has 1 manifold, 1 pump and 5 programmable stats.

There is a 5core flex going from each manifold location to the boiler location.

2 cores on each flex are not used, so at the minute when the boiler is powered, all the pumps run and the boiler pumps hot water to the manifolds constantly, even when stats aren't calling for heat.

This has been going on for ages so costing a fortune, I know that the link in the boiler needs to be removed and some sort of control put in place, but because there are so many room stats in place I'm not sure how you can get 1 to call for heat without affecting all the others.

Hopefully it can be solved using the 2 spare cores to each floor, cos getting any other cabling in is a non starter!

Not got a great deal of experience with heating but I know that whoever installed it wants a good shake.

 

[ashrow]

Is there a motorised valve on the manifolds ?
If so the boiler switched live should be operated via the valve which is operated via the individual actuator on the manifold which are opened by their respective room stats

 

[bigspark17]

there will have to be a motorized valve next to the manifolds.. this is really bad practice by alot of plumbers where they should be postioning zone valves close to the boilers to lower heat losses in other zones pipework when the boiler is operational.. are the system supplied from the same mcb or multiples.?

 

[ashrow]

there will have to be a motorized valve next to the manifolds.. this is really bad practice by alot of plumbers where they should be postioning zone valves close to the boilers to lower heat losses in other zones pipework when the boiler is operational.. are the system supplied from the same mcb or multiples.?

A lot of the manifolds i have to connect have a local valve (and these are installed as per the manifold drawing) but i also advise the plumbers to install an additional one closer to the boiler if poss where there is a large run of pipe just to reach the mainifold
I am doing one at the moment where i have a boiler in the loft (middle of the house) and there is 2 runs both approx 30 metres till the manifolds and the plumber does not want to install additional valve but i informed the client and hopefully an additional 2 valves will be installed

 

[rainstorm]

Can't remember seeing a motorised valve next to the manifolds.

The whole system is fed via one mcb, which feeds s. fused spur, which feeds boiler, pumps and all room stats.

 

[ashrow]

what boiler is installed, are there actuators on the manifold, what stats are used etc etc
If you can give me as much info as you can i will help as much as i can and if need be link you a wiring diagram etc
Alos how old is the system ie can the client not go back to the original installer ?

 

[sedgy34]

rain storm this is simple!!! take the links out just test you have a switch live at the boilers both flexes will run back to the wiring centre in the same connection you will know by looking at the flex connected in the boiler probably just connect the spare cores as the switch and connect into the sw where the link was, (post a pic if you can) underfloor heating is the easiest thing in the world when you know how to do it. i will pm you with my number if you get stuck i can talk you through it.

 

[bigspark17]

i dont see the point of putting additional valves in the create less losses in the pipe work just have all motorised valves next to boiler anyway.. and take appropriate cabling up to each manifold point ect ect ......

 

[rainstorm]

Thanks for replies.

The "wiring centre" consists of all cables from stats, actuators, pumps, feeds, stuffed into 2G back box with terminal strip. There is no dedicated control centre with electronics.

The only other time I've seen this set up there was one, which was supplied with the manifold.

2 spare cores at the boiler aren't connected at the wiring centres.

Probably going back later for another look!

 

[sedgy34]

sounds like your 2 spare cores are your switches for the boiler take link out of boiler connect switch wire, the link is causing the problems

 

[rainstorm]

The 2 spare cores aren't connected to anything at the other end Sedgy34.

By the way there was a digit missing on your pm.

 

[sedgy34]

Have an other look in your pm

 

[rainstorm]

Well I've been back, this time with a heating engineer, seems like because it is such a large house, lots of marble floor tiles, the system is designed to operate as it is.

Turning the boiler temp down should make a big difference with bills.

Having the whole system switching off would be less efficient apparantly than ticking over.

Thanks for help, and apologies to original spark, who wired it right in the first place!