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Discuss No DHW from combi boiler in the Plumbing Jobs | The Job-board area at PlumbersForums.net

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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!

20190421_132937.jpg
 
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
 
A combi should come on as soon as you open a tap, so no idea why theres all that lot in there
 
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.
 
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.
 
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
 
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.

20190421_192426.jpg
 
what about perm live and neutral also earth?
 
if your drawning is correct which im not sure is

brown should be in 1
 
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?
 
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.
 
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!
 
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
 
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
 
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
 
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.
 
You've
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
 
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?
 
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.
 
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.
 
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.

I believe that the wiring is now correct and matches that from the Grant installation manual

Screenshot_20190421-112911_Chrome.jpg
 
What should it be ? Your help is appreciated.

I offered to come and fix it for you but as my last spot for this week has been taken I won't be able to get down until Monday at the earliest.

You need someone who is competent in breakdowns and knows a bit about wiring. It should be a fairly straight forward job but get it wrong you could kill your pcb. The fact you have the wrong diagram shows that you shouldn't be touching the electrics or the boiler. If you go on checkatrade there is a bloke from helston who does both plumbing and electrics not sure if he is oil but living in helston I would of thought he would.
 
Need the right wiring to the boiler and then to confirm the boiler is doing what it should.

Once again for the hard of hearing or short of sight.

Get yourself a competent oil guy. You would have had hot water days ago.

Sometimes you need to hold your hands up and say it's beyond me. No shame in that.
 
As others have said its a combi - and as a temporary/test, feed it off a three pin plug and open up the water to its internals - if it has only been isolated for building works it will produce hot water.
 

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