Solid fuel

Hi guys been offered a job to wire a solid fuel central heating system, the controls consist of a programmer, room stat, low limit pipe stat, high limit pipe stat and a pump. There are no zone valves on the system. Anybody got wiring diagrams for this type of system.

Thanks. Alex.

I haven`t, but I would expect......

The "low limit" stat would fire the alternative heat source, where applicable, if programmer was demand.

The "high heat" stat, I would expect to override the pump; in order to "dump" excessive heat into the rads - can cause issues when the heating comes on "on its own", and the house is bouncing............

Programmer and room stat in series for "normal" heating operation.

If there isn`t an alternate heat source, then the low limit may be intended to inhibit un-necessary pump operation if the solid fuel device isn`t currenty lit.

This is all assuming a manually operated heat source ( e.g. wood burning stove). If you`ve got something like a solid fuel boiler (trianco or similar), then things are a little different.

HTH

KME

Thanks kme as you said the low limit stat is to stop the pump coming on if theres no hot water, also there is no other back up system just a log burning range cooker. Ive only worked on combi systems before so this is new to me, could you recommend a suitable timer for this system and a wiring diagram would help.

Thanks again Alex.

I think any single channel programmer; a la the "centaur" C17 (as sold by TLC).

Diagram - I`ll; see what I can manage to do after tea, unless some helpful person like JL happens to have something suitable............

KME (my diagrams aren`t the best)

i will look fo a diagram for you.

we fit the randell 103 single channel programmer,

room stat.

low limit set at 45 degrees to stop the pump running below this an causing condensation within the appliance.

high limit 89 degrees to bring the pump in if the appliance is overheating.

heat leak radiator 10% of the maximum heat output of the boiler.

ie: 35kw boiiler radiator 3.5 kw.

trv`s on all radiators except hall.

normally open zone valve on flow pipe to the cylinder and cylinder stat set at 60 degrees.

you dont need a diagram just terminate everything in a 10 way box and think it through ..

Thanks guys think ive got it sorted now, going to do job on monday. will keep you posted. Thanks again.

Alex.

alex to comply the cylinder neds a zone valve for the part L.

solid fuel is legislated by hetas .

hetas is similar to corgi or niceic etc .. a governing body

JL - thanks for the temp. settings on the pipe stats - I didn`t know those

"Scoob" for you

your welcome mate

No zone valve required for solid fuel on the flow side.

2 x Zone valves required on ch if system is split in two (eg 1 for upstairs, 1 for downstairs ).

Single channel programmer required to operate pump for ch. if only one system

Twin channel programmer required to operate pump and 2 x zone valves if system is split in two.

Dave

part l requieres water stored at 60 degrees, the only way to control it is zone the cylinder ie: normally open 2 port and cylinder stat to power shut at 60 degrees.

solid fuel is regulated by hetas if you are not hetas and not been on there training there is no way you would be able to say what is needed to comply.

zone valves are not required for the heating part of the system and are controled by the room stat and pump.

pump i also wired to come in if the appliance boils ie: over 89 degrees on the gravity pipework. pump over rides the programmer and any controls.

lastly heat leak radiator 10% of the maximum output of the appliance piped on the gravity sercs so not on the pumped side of the system.

hope this clears things up.

gas fitters cant do solid fuel even if they think they can .

Thanks for the info guys, been out and spoke to the plumber whose doing the job he says no zone valves being fitted as they fit an injector tee in the pipe work, he showed me the instalation drawings by the manafacturer ( stanley stoves) and this is the way they recommend it should be done. Jl do you envisage any problems with it being done this way.

Thanks Alex.

a plumber cant fit a solid fuel boiler, hetas registration is requiered similar to part p, a solid fuel appliance should be registrered to local building control.

to conform to current building regs stored water under part L of the conservation of energy states that water should be stored no hoter than 60 degrees. therefore a form of thermostat is req to comply. we fit normally open 2 port zone valves which is different to the powered open you would see on a normal heating. (if power shuts off it would boil up so its for safety.)

to take the excess heat away when the gravity sercs are closed to the cylinder this is when the heat leak is req usually a 1200 x 600 dc radiator on the gravity sercs .. a final safety is the high limit stat on the flow pipework that brings the pump on at over 89 degrees.

this is the way to pipe and wire a a solid fuel boiler i fit solid fuel regualrly for a local council and this is how hetas req the instalation to be completed and i have been inspected many times over the years so am 100% correct. its a actually a speciallity of mine .

in the old days we fitted injector tees to seperate the return flow of the heating and hot water to make the gravity return a priority.

there is nothing wrong with piping up a solid fuel boiler without any of the controls just gravity hot water and pumped heating and will work perfectly well but if you want it to comply all the above is req.

remember you need a certifiate of compliance as if anything happens it may invalidate your house insurance.

i will uplaod a diagram for you to the uploads section as we speak .

i placed a wiring diagram in wiring downlaods and a copy of req for a solid fuel instalation thats in the green energy bit.

the second one shows you the req and why .

Nedd Badger`s "bow down" smilie over here, for JL.

Scoobed, you are.



KME