Hot water but cold rads (HRM Wallstar 15/20)

[Cold of Cambs]

Hi there

New to the forum (first post). I've signed in as Cold of Cambs... for that is what I am.

I've had this problem once before and was told it was caused by low pressure. I now have a top-up valve which I use to ensure the boiler is at least 1bar when cold.

The firing cycle is regulated by a Danfoss programmable timer unit that has lights for both the radiators and the taps. The boiler fires fine, but only for the water from the taps, the boiler doesn't fire when the light comes on for the radiator.

I've tried bleeding the rads but they are all fine.

I would be most grateful for any advice, thanks

Cold of Cambridge

 

[Millsy 82]

Possibly 3 port valve, Stat or programmer

 

[Simon F]

try turning on the programmer for water and heating

ps-:welcome: along, hope your warm before to long

 

[SimonG]

Possiblyy pump. Hot water possibly on gravity. Does the boiler fire at all when you first switch the heating on, even for a short time?

 

[Simon F]

do you know if your set up is y plan/s plan?
one zone valve with 3 ports or two with 2
if none of the questions seem to be in your language then some pictures might help

 

[Cold of Cambs]

Thank you all for such very swift advice, I would have responded sooner but, alas, my fingers are too cold...

@Simon F - I see you have just landed from Holland, for you most definitely speak Dutch. If my plight continues for much longer however, I will do as you suggest and include some photos within this thread.

@Simon G - I'm liking the gravity/pump theory; how can I check this? No, the boiler does not fire (not even for a short time) when switched on to the rads

@Simon F - A good plan without doubt, unfortunately these run independent from each other so this option is not available (and if it were an option surely this would be a pyrrhic victory as the original fault would still be present). My thanks for your most warm welcome

@Millsy82 - (For one moment I thought it might have be compulsory to be a Simon within this thread). The stat seems to be fine and the programmer also seems to be working okay. Where do I find my 3 port valve (and what does it look like)?

 

[Cold of Cambs]

Thank you all for such very swift advice, I would have responded sooner but, alas, my fingers are too cold...

@Simon F - I see you have just landed from Holland, for you most definitely speak Dutch. If my plight continues for much longer however, I will do as you suggest and include some photos within this thread.

@Simon G - I'm liking the gravity/pump theory; how can I check this? No, the boiler does not fire (not even for a short time) when switched on to the rads

@Simon F - A good plan without doubt, unfortunately these run independent from each other so this option is not available (and if it were an option surely this would be a pyrrhic victory as the original fault would still be present).
My thanks for your most warm welcome

@Millsy82 - (For one moment I thought it might have be compulsory to be a Simon within this thread). The stat seems to be fine and the programmer also seems to be working okay. Where do I find my 3 port valve (and what does it look like)?

 

[scoullar]

sounds like zone valve to me either two or three port whatever change the head

 

[Cold of Cambs]

Hi Scoullar Thanks for the analysis. How much can I expect to pay for a new head plus labour and call out to fit it? (and what if it turns out to be the pump...? what do they cost?)

Thanks in advance!

 

[Millsy 82]

Its best to get somebody out to diagnose the fault. It usually takes a few minutes. It could still be a programmer or stat and a few little electrical checks and you will know for certain.

 

[Cold of Cambs]

Slowly getting the hang on this forum, though it appears my first reply to all your advice didn't post properly - I tried to "reply to thread", but I think my reply must still be with a moderator).

Thank you all for the very swift replies though.

@Simon F - thanks for the warm welcome. My system doesn't have an option for simultaneous operation (and if it did, surely the problem would still be there)
@Simon G - I like the pump/gravity theory. No, it doesn't fire at all when put on rads only. Is there a method to test the pump in isolation?
@Millsy 82 - the stat and programmer appear to be fine, but I agree, if I'm going to look at this thoroughly, might as well check these at the same time.

Thanks all - any idea of expected costs for pumps / heads etc?

 

[scoullar]

Hi Scoullar Thanks for the analysis. How much can I expect to pay for a new head plus labour and call out to fit it? (and what if it turns out to be the pump...? what do they cost?)

Thanks in advance!

the zone valve head around £50. labour depending on engineer, my charge would be around 60-70

 

[Cold of Cambs]

Hi Millsy 82

Thanks for taking the time to respond to my query. I have tried posting a few times to this thread but my posts generally just say “with the moderator” (perhaps they will appear in due course).

The three-port valve – I presume within the central heating system this regulates the combustion mix rather than mixing hot and cold water? Would this not be controlled by an actuator (and could it not therefore be the actuator that’s gone?)

The stat still clicks at the room temperature, so I’m guessing it’s less likely to be this (still worth checking though I suppose)

Programmer – this was my first thought as well (though again… it’s working fine to regulate timings for firing cycles). I’m also concerned that this would need an electrician to fix and not a plumber (or do plumbers get trained on how to fix these as well?)

I’m still thinking it could be the pump, but for me a bigger question right now is why does it need constant topping up if it’s supposed to be a sealed system? That means there must be a leak somewhere. Right?

But I guess the nature of this type of plumbing work means you can never properly tell until you’re on site QED bite the bullet and get a man out!

Cold of Cambridge

 

[Cold of Cambs]

thanks Scoullar (though I'm not sure it will be this as I don't have any "zones" in my house, instead every radiator has its own control)

 

[Cold of Cambs]

Hi Simon

Thanks for taking the time to respond to my query. I have tried replying to you a few times but my posts are still “with the moderator” (there seems to be quite a difference between hitting “quick reply” and “+Reply To Thread” at the top..)

I’m really liking your gravity/pump theory and, no, it doesn’t fire at all when you turn on the heating, not even for a short time.

 

[Cold of Cambs]

try turning on the programmer for water and heating

ps-:welcome: along, hope your warm before to long

Nice idea, but there isn't an option to do this (plus the underlying problem would still be there). Thanks for the well wishes... currently using a plug-in heater and jumpers!

 

[Cold of Cambs]

do you know if your set up is y plan/s plan?
one zone valve with 3 ports or two with 2
if none of the questions seem to be in your language then some pictures might help

Hi Simon

Thanks for this reply. It was indeed alien speak… but the Internet is a wonderful thing. I’ve looked at a number of plumbing plan images now and in retrospect feel I probably need to supply more information here to make diagnosis more accurate.

Deep breath.

I have a twin coil cylinder in the airing cupboard, one coil runs off the oil-fired HRM Wallstar and the other coil off an oil-fired Rayburn (I very rarely use this, just at Christmas when I need the extra cooking space). The Rayburn heats just one radiator (a towel rack I the bathroom upstairs which is otherwise cold throughout the year).

However, having looked at various images of Y plans now the thing that I don’t understand is why in my house the expansion tank in the loft is higher than the main water tank (that can’t be right.. surely?... Does that explain why it’s filled with stagnant water and why I’ve also got water constantly dripping out of the overflow pipe into the garden…)

If I have a “sealed unit” and the pressure keeps dropping (by around half a bar per hour… I have to keep topping it up) there must be a leak somewhere.

I’m starting to think I just need to get the whole house serviced at this stage, not just the boiler..

Can you recommend / can I find plumbers in Cambridge through this forum?

Thanks

Cold of Cambridge

(NB It’s my daughter’s birthday today and we really need the house heated before her party at the weekend..)

 

[Simon F]

I’m starting to think I just need to get the whole house serviced at this stage, not just the boiler..
Can you recommend / can I find plumbers in Cambridge through this forum?

sorry to hear you are still cold, like you say best to get someone in to have a look.
put a post in the "looking for a plumber" section and hopefully someone local to you can contact you through the forum.