sunvic select xl 207

[nik5]

Hi There I have been having an on and off problem with my boiler. It seems to have become non stop now. I program my unit for the hot water to go on and off at the certain times of the day. Only 1 hour for the water in the morning and evening. I only use the +1hr for the heating when ever i use it. Now for some reason when the hot water comes on and goes off the boiler remains on! And can remain on until i have at some point noticed it. Would this be a fault with the boiler/unit? Or does something need to be changed.

Please help!!!!

 

[seco services]

need abit more info on the system.
what do you do to turn it off ?
does the light on the programmer go off when the timed period has ended and the boiler keeps running ?

 

[nik5]

Exactly right. The lights turn off but the boiler keeps running! I have to keep turning it off from the mains. And then when the boiler cools down I can then turn the system back on and then have keep reprogramming it in.

 

[seco services]

do you have two of these in your airing cupboard near your pump ?

 

[nik5]

yes there are two of those.

 

[seco services]

i'd be checking the hw one is not sticking open or the micro switch is sticking on.

if you can use a multi meter you can check the better.

when the hw go's off at the programmer the valve should close and the
lever on the end should have resistance on it.
if the lever remains loose the motor has stuck open holding valve open.

if the lever has resistance i would suspect a sticky micro switch inside.

you can also check what valve wires have power on them when the programmer has gone off.

 

[nik5]

This seems to happen once the boiler has gotten quite hot. Would this suggest anything??

Also the two valves look very old, can they become defective after quite a few years? I have only been living at my house for just over a year and dont know how old they are.
And how would i check the valve wires if they have power?

 

[seco services]

Also the two valves look very old, can they become defective after quite a few years?

yes they don't last for ever.

And how would i check the valve wires if they have power?

if you follow all the cables back to the wiring centre box.
the valve will have 5 wires from it to the wiring centre.

use a multi meter to test for voltage.
with no call for hw the only wire to the valve with power should be the grey. (perm live)

call for hw from the cyl stat will put power on the brown.
when valve open and the micro switch activated the orange will become live for sw live to the boiler etc.

 

[nik5]

ok grate. ill have llook. just so iknlow, the boiler getting to hot wont really affect the electrics then?

 

[seco services]

no

 

[nik5]

hi Karl, thanks for the info the other day. I just wanted to report my problem to you again. My boiler had been working fine until this morning. As i have the hw to come on at 6am and turn off at 7am. Until i noticed the boiler was still running it was 8:15, so again its giving me the same problem and have to turn the whole thing off by the mains. Then i realised this always seems to happen when it rains. Could it be possible that water is getting in some how and causing this malfunction? Apart from the tank and the sunvic system my boiler is in the kitchen downstairs with the pipe going through the wall outside. Could water be getting into that and causing it stay on.

Any advice will be appreciated.

 

[Aragorn84]

I doubt its water related.

Your boiler will probably have three input connections, Permenant live, netural and a switched live.

Its important to understand that the time clock generally isnt connected directly to the boiler on a system like yours.

The time clock opens the motorised valves, and the valves in turn tell the boiler they're open and to start making hot water.

First of all you need to check the switched live feed to the boiler is actually live when this run-on occurs, that will tell you if somethings calling for heat and the boilers just doing what its told, or if theres a fault in the boilers control board.

If it is live, then you need to check the microswitches and motors in the motorised valves are acting properly. The simplest check is to get someone to watch the valve when you turn the system on and off at the timeclock. These valves are the most likely culprit, and depending on the model fitted you might be able to simply swap out the motorised head.

 

[nik5]

Hi Karl, again thanks for the input. I think i have identified the proeblem. I did what you said by turning on the hw and watching the lever on the motor valve. It seem to get stuck and when i do it manually the lever seems very loose. As if it has come out of somewhere.
I noticed that i have two motor valves on my boiler. 1 drayton white box and one silver.
The silver one does not seem to do anything although i can feel it vibrate when the boiler is on. What is the 2nd one for??
I am going to change the DRAYTON motor as i have got another of the same modal.

Any method of changing the motors without having to drain the system?

 

[seco services]

the other valve willbe ch

you can change the motor in the top of the actuator without draining the system.

useally its more the spindle seizing rather than the motor.

is it a ZA5/679 model number ? should be on the top of the casing.

 

[nik5]

from what i see, the hw and the ch, work on the same motor valve.. will this be a problem? If the spindle for the ch has seized is there any wy to free it or will have to be replaced?