Re: boiler doesn't respond to room thermostat

message from Steve on 9 May 2004

cheers mate! :-)

removed the actuator and the valve spindle rotates really easily and
the actuator doesn't do anything when switched so is therefore duff.

I'm a bit narked really as it was replaced at the end of March last
year at a cost of £65 so I'm not very impressed with a 13 month life
span considering the previous one lasted at least 5 years. Have now
emailed Sunvic who made it to see what they say.

thanks for the help\advice.

Steve replied to Steve on 14 May 2004

another question.....

I've had a response from Sunvic who said I should get 10yrs out of my
actuator and that it was EXTREMELEY UNLIKELY that it had failed after
a MERE 13 months! and suggested that I obtain a multimeter and test
the relay.

As it happens I'm not a sparky and wouldn't know how to use a
multimeter if my life depended on it.

However, if I unplug the relay from it's socket whilst the DHW is
being heated the boiler switches off. When I push it back in again the
boiler fires up and resumes heating water. Is this confirmation that
the relay is O.K or could it still be the cause of my problem?

thanks again for help.

Steve.

Set Square replied to Steve on 14 May 2004

Sorry, I'm not clear what this "relay" is. I'm not familiar with Sunvic
products - but most other makes have direct connections - albeit via a
junction box - between the 3-port valve actuator and the programmer, boiler,
pump, and room/cylinder thermostats.

Are you saying that your system has a relay - as in a switch operated by an
electro-magnet?

I notice that on the Sunvic website, they refer to a "Relay Wiring Centre" -
which I take to be just a junction box. Is this what you're talking about?

Please remind us of the exact model numbers of the Sunvic kit you've got so
that we can find the correct installation details on their website.

Dave Liquorice replied to Set Square on 14 May 2004

My old flat had a "flowshare" system, part of that was a box with a
relay in it that the 5(?, might have been 6) core cable from the 3
port valve connected to. This relay box had a base about 4" x 3" and
was about 3" high.

Steve replied to Dave Liquorice on 15 May 2004

sort of expected you guys to instantly know - you all being d.i.y
gurus... :lol

in the cupboard with the pump and activator are 2 boxes on the wall.
one is a simple wiring junction box. The other box contains the
relay.

The sunvic website below has the relevant images and numbers....

http://www.sunvic.co.uk/ps.htm

Top right is the relay 2272 - 337

Middle left is the Duoflow Relay wiring centre - RJ 2802

hastily chucked together web-page with better detail of my boxes and
wiring diag' at > http://www.gooduse.com/other/heating.htm

so... when I pull the relay from it's socket the boiler stops heating
water. plug it back in and boiler fires up again.

I assume that actuator sends signal to relay saying dhw or heating or
both and relay switches accordingly. I also assume that the boiler
can't respond to RFH from room stat unless actuator can rotate
accordingly, send a signal to relay which then tells the boiler to
fire up.

Is my understanding correct and can I still assume that the actuator
is knackered as it doesn't motor around or could the relay be stuck?

thanks....

Steve

Set Square replied to Steve on 15 May 2004

Also, those of us who (unlike Geoff) are pure DIY-ers will have direct
experience of only a limited number of makes and models - depending on how
many houses we've owned. We can often extrapolate that knowledge and
experience to work out what's going on with similar but different
equipment - provided we have access to the appropriate information.

Steve replied to Dave Liquorice on 15 May 2004

apparently this is a direct link to the relevant wiring diagram....

http://www.sunvic.co.uk/rjtypicalprog.pdf

which is much better than the crap image I posted!

Set Square replied to Steve on 15 May 2004

Yes, I had found it myself in the meantime, and it makes things a lot
clearer.

The fact that the hot water works with the relay plugged in but not with it
out in does *not* necessarily mean that the relay is ok!

In its un-energised state, the relay has contacts which switch the boiler
and pump on in the hot-water-only situation. Pull the relay, and the boiler
will goe off!

When heating is selected at the programmer, and the room stat is calling for
heat, the relay is supposed to switch to its energised position - which
provides an alternative supply to the boiler and does things to the
actuator. Perhaps it isn't switching when it should.

You could check this by:
* Making sure that CH is on at the programmer
* Getting an assistant to adjust the room stat so that it clicks on and off
* See what happens to the relay. If ok, you should hear it click on and off
in synch with the room stat. [If you put your thumb on it, you should *feel*
it]

If the relay *doesn't* go on and off, it could be due to:
* Duff relay
* Duff programmer and/or room stat
* Duff wiring between programmer, room stat and relay

HTH.

Steve replied to Set Square on 15 May 2004

tried all that. I can see both sets of contacts that the relay
switches between and nothing happens. the thermostat has been
replaced as I assumed it was that that had failed in the first place.

it seems unlikely that the wiring has suddenly devoloped a fault so
I'm going to replace the relay I think. It's currently the number 1
candidate and a new one is only a few ££££.

let you know.

Archived message: Re: boiler doesn't respond to room thermostat (UK D-I-Y House Repairs)