New CH system underpowered/ wrong layout?

[Alex100]

There is about 75mm of loft insulation.
QUOTE]

Wel there's a big part of your problem.

That's on my list. It's under boarding and carpet, so it's not a weekend job. Still, the heating system was installed knowing what is in the attic and I was never asked about that.

 

[mfgs]

I did a rough calculation on the lounge as per the info you gave and got about 2.2kw which I think is approx 7500btu's, so that one looks undersized.

 

[chris watkins]

Chris

Should he have a design and written calculations then? He said to me he used an online BTU calculator that he found very reliable and I did think blimey, I could do that myself (which I have many times, and his rads are either too small or marginal at best, depending on the website).

It is sounding like I need to find a respected heating surveyor and get this checked before he starts putting bigger rads in and charging me. He has said 4-6 weeks to put bigger rads in - I refused to just pay and said I'd ay the difference in cost of the rad for the lounge, dining and bathroom rads to be upgraded (not labour or other materials). Maybe others will find that the whole system is under powered and that will get interesting - I'd def need an independent report then.

Many thanks
Alex

You have to be fair to this guy & give him both the chance to show how he has size / designed the system to do the job you have paid for & if any mistakes have been made to correct these. Not withstanding that, the product he has provided you does not appear to be fit for purpose, he is obliged to provide information to show how he selected the components to do an acceptable job, what ever form this took (there are too many variables to start second guessing) with that info you can then see wether it is both works / is designed within the normally acceptable standards.
He can not make a charge of any kind (for the rads) for correcting his mistakes unless you had some kind of input into selecting these.
You need to write to him setting this out & tell him that 4-6 weeks is no good.

 

[aladin]

as previously said,
all seems well apart from the heat pack so undersized rads dont hang the guy simply ask the chap to recalculate and replace

 

[MRDrip]

Are all your "external walls of 18inch stone & rubble," the same ? is there any internal insulation on the walls?
Just wondering how many tons of stone need to be heated to warm the building.

 

[bewsh]

These online radiator sizing sites generally tend to over size them as it's difficult to accurately size a radiator without knowing the exact u values of the building materials in the property.

Also something to be mind full of is that for energy efficiency you have to follow building regulations/british standards which state the temperatures for each type of room, ie lounge=21C, bedroom=16-18C, or something like that.

 

[josh]

Simple thing, is the boiler stat turned up?
not another 'oh we'll set that at 45c to condense more' then wonder why rads only get warm.

 

[SafeGasInstall]

good work Josh

 

[Centralheatking]

Josh is right in some ways - in order to get these 'intermediate tech' condensing boilers to perform properly I understood the installer has to undersize the boiler in order to get it to operate at peak performance - that way it recovers the heat.

Mind you John Prescott was the minister that over saw this legislation - he was good with his fists but maybe not with a technical issue - he seemed to shoot from his hip and
sometimes below that - as his wife found out


centralheatking

 

[vern]

Simple thing, is the boiler stat turned up?
not another 'oh we'll set that at 45c to condense more' then wonder why rads only get warm.

Sorry to disappoint guys ........re read post number 1 the boiler radiator thermostat is set to max, which means flow of 88 degs, rads are undersized!

 

[richardgas]

has he put a room stat/programmer in correct position and in the hours it takes to heat house are all the rads hot to touch or just warm

 

[Nostrum]

He's probably used an online calculator which doesn't have the option of choosing rubble walls, I haven't seen many that do. If he's sized the rads for a cavity wall build with insulation etc, your going to be at a loss.

vern, are you saying the code plug allows the boiler to modulate lower than the minimum stated output? Most are able to limited the maximum output but the minimum remains the same.

 

[doitmyself]

in order to get these 'intermediate tech' condensing boilers to perform properly I understood the installer has to undersize the boiler in order to get it to operate at peak performance - that way it recovers the heat.

Whoever told you that didn't know what he was talking about!!

If a house has a 10kW heat loss it needs a 10kW boiler. Putting in a 5kW will just mean that the house will only reach the required temperature (21C) if the outside temperature is above 10C!

Heat recovery, i.e condensing, only occurs if the return temperature is below 55C; the lower it is the greater the condensing effect. Most boilers are designed to work with a 20C differential, which means a flow temperature of 75C if you want the return to be 55C. Unfortunately this reduces the output of radiators by about 15%, so you have to install rads which are 20% oversized.

 

[Alex100]

has he put a room stat/programmer in correct position and in the hours it takes to heat house are all the rads hot to touch or just warm

all hot to touch. i bleed regularly, which is the installer's mantra, but rarely any air.