Boiler delivers hot water but no heating - what's going on?

[Davycrocket]

Hi mandate
I agree with what you say.
When I originally said that the switch is made when the lever is pushed all the way across, I was explaining to saintgeorge the difference between two test he did, and he could not understand why. He thought it was a sequence problem.
remember, his water heating only was always ok.
Now :-
ref the testing of the C heating with water off at the timeswitch..
In one test he switched on the C heating at the timeswitch, and made sure that the room stat was calling . The boiler didn't fireup on its own but did so when he pushed the lever to the right and went off again when he released the lever.

In another test with the water heating still off and C heating turned to off at the timeswitch, he latched the lever in the manual notch probably thinking that this was the same as pushing the lever to the right . then when he went and turned the heating on at the timer the boiler did not fire up . As I said earlier he was puzzled as the two results were different and he expected them to be the same , ie the boiler to fire up.

My statement that has caused the controversy was my explanation that the difference was that when the lever is pushed to the right a switch is operated which fires up the boiler. That statement is perfectly true. The fact that the switch transfers a little further to the right than where the lever in the notch was holding the quadrant , but actually before the lever is at the extreme right is irrelevant.

 

[saintgeorge]

The electrics in my cupboard are a bit dodgy so it is conceivable I have got a loose connection to the valve top motor somewhere.

I ran the test David C offered on 12 Dec. Tests 1 and 2 checked out OK. With HW (only) on at timeswitch, all stats calling, I moved the lever to the notch position. Boiler and pump stay on, but as David predicted, rads do heat up.

However, I was stumped by test no 4 and didn't want to try it out. With HW off and CH on, the motor if still ok SHOULD run to the heating position only, boiler and pump continuing to run. However if I've got the lever in the notch, won't this prevent the motor running to the heating only position? Do I have to release the lever to run this test?

Also, don't quite understand the refs to orange and grey wires. As far as I can see I have only got one 240V cable entering the motor box, and it's black. Is this a ref to wires inside the motor perhaps?

 

[Davycrocket]

Hi saintgeorge

Ref the lever in the notch question

The lever is not connected to the quadrant that does the water valve/ electrical switches movement , it just pushes it to the right. So with the lever in the notch, the motor if it was good, could still move the quadrant to the heating only position.

Ref the cable to the 3 way valve.

You can only see the cable sheath. Inside it are 5 wires .
1 green and yellow stripes (IN) is the earth
2 grey (IN) is ' hot water NOT calling'
3 white (IN) is 'central heating calling'
4 orange (OUT) is 'fire up the boiler when central heating only is
calling.
orange (IN) is de-polarize the motor in case it has become
magnetized whilst stalled at mid position because water and
heating were calling, and heating suddenly becomes satisfied.
The spring has to be able to drag the motor backwards to get the
valve back to the water only position
5 blue neutral feed to the synchron motor.

If you are still puzzled give me a call on 01925 213446 or
Mob 07773728651 Rgds David C

 

[KM10]

I found this very helpful:

http://www.diyfaq.org.uk/plumbing/controls/midpositionvalve.htm

(They say a picture can replace a thousand words)

regards

KM

 

[Davycrocket]

Hi KM10
Yes, the circuit is fine . SW1 and SW2 are just a little confusing . People need to know that on SW1 although it doesn't look like it on the ' typed' circuit, the common is the lower terminal connected to the motor, and on SW2 the common is the top terminal, connected to the white wire.
The text also explains what I had mentioned about the motor becoming magnetized when locked ( by DC pulses) in the mid position. Rgds David C

 

[dingodeano]

just wanted to mark this as an interesting topic. or for you forum savy folks....BUMP .!

 

[themoogie]

hi have the same issue
have tried the tests described and have the same results

are the motors vendor specific? wehres the best place to purchase
and brand recommendations

cheers

 

[Davycrocket]

Hi there
The same motor fits many two way valves. You can buy just the motor at any plumbing suppliers, or much cheaper if you are on EBAY.
Try searching on 'SYNCHRON MOTOR' The motor is quite easy to change and has only two wires which can be connected either way around.
Rgds

 

[themoogie]

ordered
thanks for the help