Could someone help me understand my hot water issue?

[Naydnay]

I have no hot water, could anyone help me troubleshoot? Many thanks in advance for any help. See photo attached of my set up.

1) I have a system boiler + unvented cylinder all new installed about 9 months ago.

2) Heating is working fine - turning up temp on Nest app fires up the boiler and rads get hot

3) When I use the app to tell it to make hot water, the boiler does not fire up.

4) I DO get hot water, if I request hot water at the same time the heating is on.

5) There are 2 motorized valves in my set-up. One of them is a Corgi 2 port zone valve (green circle in photo). This starts buzzing when I request hot water.

6) The other is a Honeywell (red circle), which says 'Hot water only' on a sticker on the side. Don't hear anything from this.

7) They both have a manual sliding switch on the side of them saying 'manual open' which I have tried, but this doesn't do anything.

8) Boiler is a Vaillant EcoTec Plus 630

9) Because we are getting hot water when the heating is on, I can't be sure how long this problem has been going on for... certainly in the past few months our heating would have almost always been on in the early morning when the hot water is scheduled.

 

[Madrab]

If it's only in 9 months then you need to get the installer back in - I presume the work is guaranteed?

It could be a 2 port valve issue.

 

[Johntheo5]

I have no hot water, could anyone help me troubleshoot? Many thanks in advance for any help. See photo attached of my set up.

1) I have a system boiler + unvented cylinder all new installed about 9 months ago.

2) Heating is working fine - turning up temp on Nest app fires up the boiler and rads get hot

3) When I use the app to tell it to make hot water, the boiler does not fire up.

4) I DO get hot water, if I request hot water at the same time the heating is on.

5) There are 2 motorized valves in my set-up. One of them is a Corgi 2 port zone valve (green circle in photo). This starts buzzing when I request hot water.

6) The other is a Honeywell (red circle), which says 'Hot water only' on a sticker on the side. Don't hear anything from this.

7) They both have a manual sliding switch on the side of them saying 'manual open' which I have tried, but this doesn't do anything.

8) Boiler is a Vaillant EcoTec Plus 630

9) Because we are getting hot water when the heating is on, I can't be sure how long this problem has been going on for... certainly in the past few months our heating would have almost always been on in the early morning when the hot water is scheduled.

View attachment 340202

The blue one looks like it should be the HW motorized valve and the honeywell red circled one, the heating motorized valve, are there any other motorized valves in the system?

 

[stem]

Inside each of the valves is a small microswitch controlling the boiler. When the valve opens the microswitch operates and the boiler springs into life. From you description of the symptoms it would sound like the microswitch inside the hot water valve has failed, (or there is a broken connection somewhere) so that the valve opens OK, but the switch doesn't operate. Then when the heating valve opens, its switch operates the boiler and because the hot water valve is already open, the hot water heats up too.

A bit unusual that in a new installation the valves are different, has one been replaced already?

I didn't reply earlier, because looking at your photo and your description I couldn't marry the two together, however, I think @Johntheo5 has nailed why.

 

[Naydnay]

Thanks very much for your responses that makes a lot of sense now. Not sure why the valves are of a different make, nothing has been changed until now

Curious about the ‘hot water only’ label on the Honeywell box… is it a problem that they have connected this to control the heating?

 

[Bod ...]

Is your heating working?
What does the pressure on the boiler read?

 

[stem]

Curious about the ‘hot water only’ label on the Honeywell box… is it a problem that they have connected this to control the heating?

Not if it was working correctly before the fault occurred. It sounds more likely that just the label is wrong. If they were transposed electrically the hot water would come 'on' when the only the heating should be 'on' and vice versa.