No DHW from combi boiler

marcuspreedy · Apr 21, 2019

Hello

I am having to replace the unvented hot water system in my property, and as a temporary measure to get DWH downstairs I have un-isolated the supply from my Grant combi boiler.

But, no hot water is forthcoming! I think it may be a problem with the Danfoss set3e programmer which a builder removed and replaced during renovation works.

I have attached a photo of the wiring, and it looks to me if there should be a wire going into terminal 1 (Water-On) but which wire?

Hope someone is able to help!

Rob Foster · Apr 21, 2019

Oh dear, If your not qulified you really must not be in there .
Get an Engineer in .

Shaun ....

centralheatking

ShaunCorbs · Apr 21, 2019

tbh your best guess is same as ours depends whats connected at the other end could be grey but who knows

best get a pro in to check what the builder has done / disconnected

townfanjon · Apr 21, 2019

A combi should come on as soon as you open a tap, so no idea why theres all that lot in there

Burger · Apr 21, 2019

That just looks like CH wiring. Looking at the diagram there’s no wires for dhw. As TFJ has said it’s a combi, so open a tap, should get dhw, if you’re not then employ a GSR who can work on boilers.

Thanks.

SimonG · Apr 21, 2019

CBW1982 said:
That just looks like CH wiring. Looking at the diagram there’s no wires for dhw. As TFJ has said it’s a combi, so open a tap, should get dhw, if you’re not then employ a GSR who can work on boilers.

Thanks.

For a grant then he will need a good oil engineer.

ShaunCorbs · Apr 21, 2019

townfanjon said:
A combi should come on as soon as you open a tap, so no idea why theres all that lot in there

oil combi needs a two chanel prog for the store etc

marcuspreedy · Apr 21, 2019

Thanks for your suggestions so far, I managed to do a bit more investigation and have come up with the following wiring plan.

The DHW switched live from the boiler appears to go to the HTG com on the programmer, which doesn't seem right to me.

It's an oil combi! No requirement for Engineer to be GSR.

ShaunCorbs · Apr 21, 2019

what about perm live and neutral also earth?

marcuspreedy · Apr 21, 2019

ShaunCorbs said:
what about perm live and neutral also earth?

I've left them out for clarity !

ShaunCorbs · Apr 21, 2019

if your drawning is correct which im not sure is

brown should be in 1

marcuspreedy · Apr 21, 2019

ShaunCorbs said:
if your drawning is correct which im not sure is

brown should be in 1

The drawing is correct.

I agree it would make sense that brown (from boiler) should go to 1.

I'm going to try that now!

Stu-B · Apr 21, 2019

If the brown is supposed to be in no1 then surely at the moment it would make the DHW be permanently switched on as it’s connected to the looped permanent live.
But you say you’re not getting any hot water. Where is the grey wire connected at the other end?

marcuspreedy · Apr 21, 2019

Stu-B said:
If the brown is supposed to be in no1 then surely at the moment it would make the DHW be permanently switched on as it’s connected to the looped permanent live.
But you say you’re not getting any hot water. Where is the grey wire connected at the other end?

The Grey wire is not connected at either end.

marcuspreedy · Apr 21, 2019

Update!

I have now put the brown wire (SL-DHW) into terminal 1.

The water from the tap is no-longer at incoming temp of 8°C, but only reaches 24°C briefly and then falls away!

marcuspreedy · Apr 23, 2019

Still no hot water! Nothing I do will activate the burner to supply hot water. Even the small amount of stored water in the boiler is not getting hot!
Any ideas

Stu-B · Apr 23, 2019

Could be a number of things stopping the boiler getting to the ignition stage, time to get a pro involved.

Dake205 · Apr 24, 2019

I don’t see grey wire on drawing but would suggest it’s either linking 1-2 or through grey wire if that make sense don’t know oil boilers, is there an external control on heat store similar to cyl stat

Dake205 · Apr 24, 2019

Sorry opened on page 2 and went back only seen your pencil drawing, there is nothing in 1 lol you would have to look at internal boiler wiring and make link for hot water back in there

marcuspreedy · Apr 24, 2019

Dake205 said:
Sorry opened on page 2 and went back only seen your pencil drawing, there is nothing in 1 lol you would have to look at internal boiler wiring and make link for hot water back in there

The brown wire from boiler now goes into terminal 1, but there must be something else stopping the boiler ignition.

Coby kenny AGUILAR · Apr 24, 2019

You've

marcuspreedy said:
The brown wire from boiler now goes into terminal 1, but there must be something else stopping the boiler ignition.

They're was no need to change around the wires, now you have created a hazard.

Your issue is clear in your original post and easily resolved however they're maybe a reason why it was left like this, get a professional

marcuspreedy · Apr 25, 2019

Coby kenny AGUILAR said:
You've

They're was no need to change around the wires, now you have created a hazard.

Your issue is clear in your original post and easily resolved however they're maybe a reason why it was left like this, get a professional

So you are saying that the DHW switched live wire should be connected to the permanent live loop, with nothing connected to the terminal 1(DHW-On)? That doesn't make sense!

The danfoss programmer was replaced by a builder when the original was damaged during the removal of the wall to which it was attached. He knew we only used the CH, and presumably wired it as such.

So if my issue is clear & easily resolved what the solution?

SimonG · Apr 25, 2019

Get a professional in. Job sorted.

Millsy 82 · Apr 25, 2019

Your problem is that the wiring you have going to that programmer is incorrect if what you are saying is correct. I wouldn't go just trying to put wires in different places as pcb's don't like things like that.

As Simon has already said get a professional in not a builder but an oily a good one will be able to assess your wiring and put it right.

Millsy 82 · Apr 25, 2019

Actually I've just seen your from the lizard where abouts on the lizard? I charge a fixed price for diagnosis a little bit more for the lizard though as it is a bit of a trek for me. Let me know early enough I may be able to get to you late afternoon.

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No DHW from combi boiler

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