New CH system underpowered/ wrong layout?

[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.