Rehema 28s Central Heating Strangeness

[jabei]

Hi.
I have just moved into a house with quite a strange set up.
A Rehema 28s boiler downstairs with an internal timer and a wireless room thermostat.
Upstairs is another timer (Sunvic) next to the hot water cylinder.

It seems both timers need to be set at the same time for the heating/water to be heated.

If the Sunvic has the HW on and the Heating in any position except off (all day/advance/program)...I get heat in the radiators regardless of whether the program is within my timings or not.

The room thermostat doesn't have any effect on the boiler if it is within timer "on" times.

oh...and radiators all have thermostats on them as well, but are either boiling hot or freezing cold and don't seem to turn off at any point, even though the place is sweltering.

I seem to have an awful amount of equipment that provides me with a really bad system.

Not sure if there is any advice that can be given or anything I can try?

What I waould like is for hot water to be relatively on demand and for the room thermostat to have some effect.

Any help gratefully received

 

[gremlin16]

Its probably wrongly wired to European design

 

[jabei]

I forgot to mention that the boiler appears to be set to control Hot Water only.

 

[gremlin16]

I forgot to mention that the boiler appears to be set to control Hot Water only.

Not sure what you are trying to say.

If boiler is set for HW only, what heats the central heating. ?

 

[jabei]

Exactly !!
The bolier can be set to Water only...Heat only...or both. And it's definitely on HW only.

 

[gremlin16]

Time to call someone in. Looks as the system has not be wired correctly.

Call a reputable GSRengineer to check it out.

 

[Agile]

You seem to have a combi boiler being used to heat a cylinder. Thats fine but seems to be wired wrongly.

Usually the combi output would supply one hot outlet, usually the kitchen.

The TRVs seem to be failed.

I also think you need a competent engineer.

Tony

 

[gremlin16]

Just reread OP.

A Rehema 28s boiler

?? No such boiler.

"S" is a system boiler sized 18s, 24s, 30s

"C" is a combi sized 24c, 28c, 35, c39c

You may be right with your assumption Tony.

 

[jabei]

Sorry...it 24s.....definitely not a combi

 

[D_Hailsham]

I forgot to mention that the boiler appears to be set to control Hot Water only.

Are you saying that parameter P3 is set to 3? System boilers should be set to 2.

Is the internal clock the same as the one in these Instructions? If so, is it the single or two channel version?

The way to tell if it is the single channel is to set the HW to off and then see if the boiler still lights when HW is called. This is because the HW is wired to be permanently ON in a single channel timer.

Is the Sunvic a single two channel timer?

 

[jabei]

Yes...Parameter is 3.

It's that timeclock and it has settings (on/off times for both water and heat)
Not sure how to set HW to off ...seems as though off controls the whole thing. Not a separate switch for HW and heat

I believe the Sunvic is two channel.

 

[D_Hailsham]

Yes...Parameter is 3.

It should be 2 for a system boiler! So the first thing to do is to set it to 2.

It's that timeclock and it has settings (on/off times for both water and heat). Not sure how to set HW to off ...seems as though off controls the whole thing. Not a separate switch for HW and heat

It's can be worked out from the instructions, but not easily.

When the top RH switch (Run, P1, P2) is in P1 position you can set the heating times and when in P2 you can set the HW times. You put it in the Run position to work.

Set some CH (P1) and HW (P2) times (see the Instructions) and make sure that there is a time band when neither are supposed to be ON. Now set the switch to Run. Set the other switch to Auto.

Temporarily alter the clock so the time is some where within the HW OFF and CH OFF band. Now turn up the thermostat on the HW cylinder to max (you may have to turn the Sunvic on as well). If you have a single channel Remeha timer the boiler will still light, even though it is not supposed to. If it doesn't light, you have a two-channel timer.

Does the Sunvic have switches/buttons for heating and hot water? If so it's a two channel timer. If you post a pic or provide the model no we can verify this.

 

[jabei]

This is great help...thanks....

The Sunvic definitely has both water and heat.

I'm not sure where the thermostat on the boiler is though.

 

[D_Hailsham]

I'm not sure where the thermostat on the boiler is though.

I didn't say anything about the boiler thermostat. It's the one on the side of the HW cylinder which you have to turn up. It looks similar to this:

View media item 10596

 

[jabei]

I don't see any thermostsat unfortunately.
Nothing fires on the boiler.