I have central heating but no hot water

[Kotek Besar]

My central heating is working, but I have no hot water.


My boiler is an ideal logic heat 15. I have hive active heating.


When I turn the central heating on in the Hive app, the hive receiver calls for central heating and the boiler fires up. It is working correctly.


When I turn the hot water on in the Hive app, the hive receiver calls for hot water but the boiler does not respond. It remains in standby mode.


I read online that the issue may be a problem with the 2/3 motorised valve in the airing cupboard. Mine is a danfoss hsa3. So I just bought a new one and replaced it like for like. But the issue remains.


Any advice welcome.

 

[townfanjon]

You need to find out of your cylinder stat is “ getting a live “ , has anybody knocked it , is it an unvented cylinder?

 

[Riley]

Or the two/three port valve

 

[Kotek Besar]

You need to find out of your cylinder stat is “ getting a live “ , has anybody knocked it , is it an unvented cylinder?

Thanks for replying. How can I check if it is getting a live? I don’t believe it has been knocked recently, but I suppose it is a possibility. I’m sorry, I don’t know what unvented means.

 

[Riley]

Do you know how to use a multimeter? If not you’ll need a heating engineer out

 

[Kotek Besar]

Do you know how to use a multimeter? If not you’ll need a heating engineer out

Afraid not. There is a plumber who I usually use to service my boiler and to be honest it is due a service this month so I could call him to do both at the same time. But, from what you’ve said, is it a plumber I need an electrician?

 

[townfanjon]

Thanks for replying. How can I check if it is getting a live? I don’t believe it has been knocked recently, but I suppose it is a possibility. I’m sorry, I don’t know what unvented means.

You would need to know how to use an electrical tester.
The “unvented”bit is a pressurised water cylinder which is fitted to most new build houses these days , you may have an older type “vented “cylinder .

 

[Riley]

Either way I’d get your man in

 

[Kotek Besar]

Thanks everybody. I will get my man in.

I actually electrocuted myself today changing the Danfoss unit over. I isolated the electrical circuit on the fuse board that is labelled “water heater” but it was still live! An electric shock later, I went back downstairs and isolated the mains completely before going back upstairs to finish the job. Of course, it was all in vain as the issue remains!

 

[Riley]

Good choice to get someone in

 

[Pickwickpick]

Thanks everybody. I will get my man in.

I actually electrocuted myself today changing the Danfoss unit over. I isolated the electrical circuit on the fuse board that is labelled “water heater” but it was still live! An electric shock later, I went back downstairs and isolated the mains completely before going back upstairs to finish the job. Of course, it was all in vain as the issue remains!

You've learnt a very useful lesson, never assume you've successfully isolated the power, always test it before touching anything!

 

[Murdoch]

FWIW “water heater” is normally the immersion.

The boiler would usually be on a different circuit, hence why you gave yourself a shock ......

 

[Kotek Besar]

The only other circuit it could’ve been on is upstairs sockets. It wouldn’t have been on upstairs lights and all the other circuits relate to downstairs. Bit weird. Electric shock was not fun.

 

[garygvl]

Thanks everybody. I will get my man in.

I actually electrocuted myself today changing the Danfoss unit over. I isolated the electrical circuit on the fuse board that is labelled “water heater” but it was still live! An electric shock later, I went back downstairs and isolated the mains completely before going back upstairs to finish the job. Of course, it was all in vain as the issue remains!

you probably turned the immersion heater off as murdoch said

 

[Burger]

As pickwickpick said a lesson learned. Safe isolation involes dead testing, otherwise that’s how you’ll end up, dead. Regarding your issue, it could be the 3 port wiring set up. Did it work before? Is your cylinder stat on correct temp and correctly attached? Have you tried heating and hot water together, does the pipe feeding the cylinder coil get hot?

 

[Kotek Besar]

It has worked fine for the past three years. Thinking about it, I change the batteries in the hive thermostat two days ago. I think this was about the same time as this issue happened. Coincidence?

 

[Burger]

It could be. Try the heating and hot water together, see if the hot water circuit (coil) heats up, if it does then it’s probably the 3 port valve, if it doesn’t then look at something else.

 

[SJB060685]

Like said above you probably switched the immersion heater off. Sometimes heating circuits are wired to their own circuit off main fuse board, other times they’re spurred off a socket circuit. They shouldn’t be wired into a lighting circuit as this will most likely cause nuisance tripping when multiple outlets are working.
Either way lesson learned lol.

 

[Kotek Besar]

Just got home from work. Newly fitted Danfoss 3 way valve is in auto. Central heating demand is on. Hot water demand is off. However, water is hot and all visible copper pipes in this picture are hot:

 

[SJB060685]

Valve around wrong way?

 

[SJB060685]

Nope scratch that lol

 

[Kotek Besar]

Right, I know this seems to defy logic but here goes.

I’ve just opened a hot tap and wasted all the hot water and kept it running until it ran cold.

I then used the Hive app to boost the hot water for 30 minutes, which correctly caused the hive receiver connected to the boiler to set hot water demand on. As if by magic the boilet responded correctly and fired up, quite normally. Remember, the issue I’ve been having is that the boiler has been ignoring this hot water demand and remaining in standby.

After two minutes, I used the Hive app to cancel the hot water boost, it duly stopped the hot water demand at the hive receiver and the boiler stopped firing and put itself into standby. All good.

I think the best thing to do now is leave the central heating off tonight, set the hot water to heat from 6 am to 6:30 am (which is what it’s usually set for) and I’ll report back tomorrow as to whether or not I get a hot shower in the morning!

 

[Burger]

I wonder if it was just a satisfied demand? (Up to cylinder stat temperature).

 

[Harvest Fields]

Thanks everybody. I will get my man in.

I actually electrocuted myself today changing the Danfoss unit over. I isolated the electrical circuit on the fuse board that is labelled “water heater” but it was still live! An electric shock later, I went back downstairs and isolated the mains completely before going back upstairs to finish the job. Of course, it was all in vain as the issue remains!

I would get myself checked out if it was a big shock. It doesn’t take much to knock the heart out of sync. Better safe than sorry.

 

[Kotek Besar]

Good morning.


Today I had a hot shower.


Here is a summary of events:


Before I went to bed I set the CH to be off all night. That is, set not to call for CH at all.


The HW was timed to come on from 06:00 - 06:30. It did. The call for HW was made, the boiler responded correctly and hot water was produced. Perfect.


We consumed all the hot water and made sure it was all used by opening the HW tap and confirmed it as running cold. CH is still off. In the airing cupboard, all the copper pipes in the picture (prev post) are cold. So everything is now cold, as it should be.


Next, I used the hive app to turn on the CH, the call for CH was made, the boiler fired up, CH initiated. In the airing cupboard, the A and the AB pipes are warm, the B pipe is cold. That’s looking good and tells me the newly fitted Danfoss 3 way motorised valve is working correctly, feeding the CH but not the HW, as per current demand.


15 minutes later, I felt all the rads. They’re hot. I opened the HW tap to test and water is cold, as expected. I used hive app to boost HW for 30 minutes. Checked hive received connected to boiler, it’s now calling for HW as well as CH. Looking good. Up in the airing cupboard, All copper pipes now hot. 30 minutes later, HW tap runs hot.


So I’m tempted to now say, issue resolved and everything is now working as expected. Thanks to everyone for all their valuable help. As you can probably tell, I’m no expert in this area - but I want to learn.