New Boiler Fitted All Radiators Hot But Strange Issue
- Thread starter Bsociable2
- Start date
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The boiler is out in the utility room. The old boiler got hot so it heated up that room but now the boiler stays cool that room is cold but we just shut the door from the utility to the kitchen. The new boiler has built in frost protection which I think means will cut in if it gets too cold.
Willing to try anything though so thanks for your suggestion of leaving it on all night. What temp do you think we should set it to?
D
Dean744PiN5
And there neighbours, neighbour 
you would be surprised how many around the country are living with this just thinking that's how a condensing boiler should work.
I had 1 customer who's vaillant boiler was doing this for 3 years and they just thought it was normal. Of course it's not the boilers fault though, to some extent I don't even blame the installer, but the lack of education and information that is out there for the installer.
you would be surprised how many around the country are living with this just thinking that's how a condensing boiler should work. I had 1 customer who's vaillant boiler was doing this for 3 years and they just thought it was normal. Of course it's not the boilers fault though, to some extent I don't even blame the installer, but the lack of education and information that is out there for the installer.
A
ALEC1
10 radiators on 30kw... madness.. I have 8 radiators on 5kws to give you an idea.
Dean's diagnosis is spot on..
your best bet is to invest in vaillants controls so you can lower the heat output in heating to a more sensible size...
Dean's diagnosis is spot on..
your best bet is to invest in vaillants controls so you can lower the heat output in heating to a more sensible size...
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A
ALEC1
great Dean, a man who sees the failings in our industry and does not idly blame installers...thats refreshing..
As mentioned in another thread, I call this the "Spinal Tap" method of system design (or lack of).
OP, set the boiler parameter d.0 to 12 and see if that helps.
OP, set the boiler parameter d.0 to 12 and see if that helps.
I'm really sorry but I don't understand what you guys are saying. Please can you explain in baby talk (sorry). I think you're saying the boiler is too big for our needs? Our house is a fair sized detached. The installer was originally going to put in 24 but said if we bought the 30 there was only an £80 difference and that's why he installed the 30. Have we done wrong???
D
Dean744PiN5
Do as Dan says and you should be fine.
i've always felt that there was never enough info readily available to the installer in all aspects of condensing boilers from installation to service to repair.
i've always felt that there was never enough info readily available to the installer in all aspects of condensing boilers from installation to service to repair.
A
ALEC1
yes, over sizing boilers is very misguided..and with respect what do you know about heating technology?
most pros calculate boiler size as 1kw per radiator and 1 for the pipe work... even that over sizes a fair bit.
as said upgrading to vaillants controls will resolve the issue...where in London are you...
most pros calculate boiler size as 1kw per radiator and 1 for the pipe work... even that over sizes a fair bit.
as said upgrading to vaillants controls will resolve the issue...where in London are you...
Thanks everyone for your help. I'm really grateful. Will ask hubby to read this thread when he gets in and do as you say. Keeping everything crossed. We have spent in excess od £3K for this so I hope it works. Just for the record the temp now after hours of being on is at 19C. Not warm enough for me (sigh). I'll let you know how we get on. Thank you xxxx
Thank you for replying. Sounds like we didn't research enough and went with what we were told. What do you mean by Valiant controls? We have individual thermastat on each radiator.
A
ALEC1
I am a toasty 21c with my boiler rated to 5kws...down rating to 12kws will help on heating but make hot water heat up a bit longer... hence the need for vaillants controls...
OP... My house would traditionally have 12 or 13 rads.
It is well insulated.
My boiler is hobbled to something like 11 or 12 kW at the moment and it barely ever goes much above 4 or 5 kw or heat output.
Not counting hot water!!!!
As has been said here already - your boiler is ridiculously over sized and spends half its time wondering what to do with itself. It ramps up to full temperature so quickly that it shuts down and enters an anticycling program.
Setting D.0 to 12 will limit the boilers output to more closely match what we have GUESSED is better for your house. It is scary and frustrating that we can usually suss these problems out over the internet and the installer who is there and hands on doesn't.
It is well insulated.
My boiler is hobbled to something like 11 or 12 kW at the moment and it barely ever goes much above 4 or 5 kw or heat output.
Not counting hot water!!!!
As has been said here already - your boiler is ridiculously over sized and spends half its time wondering what to do with itself. It ramps up to full temperature so quickly that it shuts down and enters an anticycling program.
Setting D.0 to 12 will limit the boilers output to more closely match what we have GUESSED is better for your house. It is scary and frustrating that we can usually suss these problems out over the internet and the installer who is there and hands on doesn't.
D
Dean744PiN5
the easieist way to explain it is, your radiators can only give out a set amount of heat relative to there size.
For example a 600hx1000w could be 1kw (it might not be but haven't got a rad sizing table near by) so if you had 10 of these your system would need 10kw of heat (not taking cylinders into account here)
So you would match to the boiler closest but higher than that output say a 12kw boiler.
now lets assume your rads have a max total output of say 15kw your current model has double the capacity (30kw)of what your system can chuck out in heat.
Now the common misconception is that "if i put a bigger boiler in it will handle the cold better" this is incorrect because your rads can only give out there designed output and nothing more regardless of boiler size.
The consequence of this is an "oversized boiler" in simple terms your boiler is producing more heat than the rads can handle so it switches itself of for several minutes until the temp of the system water drops 10-15degs (this is called short cycling).
To be running efficiently a condensing boiler actually needs to be running continuously rather than cycling, it achieves this by modulating (varying) the quantity of gas it burns as the system water starts to reach temp to keep it at a constant as long as possible until there is no call for heat.
to combat this problem you need to match the output of the boiler to the output of the system as Dan says in the parameters menu.
For example a 600hx1000w could be 1kw (it might not be but haven't got a rad sizing table near by) so if you had 10 of these your system would need 10kw of heat (not taking cylinders into account here)
So you would match to the boiler closest but higher than that output say a 12kw boiler.
now lets assume your rads have a max total output of say 15kw your current model has double the capacity (30kw)of what your system can chuck out in heat.
Now the common misconception is that "if i put a bigger boiler in it will handle the cold better" this is incorrect because your rads can only give out there designed output and nothing more regardless of boiler size.
The consequence of this is an "oversized boiler" in simple terms your boiler is producing more heat than the rads can handle so it switches itself of for several minutes until the temp of the system water drops 10-15degs (this is called short cycling).
To be running efficiently a condensing boiler actually needs to be running continuously rather than cycling, it achieves this by modulating (varying) the quantity of gas it burns as the system water starts to reach temp to keep it at a constant as long as possible until there is no call for heat.
to combat this problem you need to match the output of the boiler to the output of the system as Dan says in the parameters menu.
D
Dean744PiN5
all those reply written in the time it took me to write above post, bloody ipad keyboard
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