Urgh!!!! This is a nightmare please help!

[samdnorf]

Ok I'm sure this has been asked so many times but I am getting completely confused I am currently gettng quotes for boiler replacement as our POWERMAX 185 boiler has got to the point of time to change. I like the idea off a water store as I have 2 showers (mains supplied) and bath, 4 Bedrooms (all decent size i.e. the smallest room can fit a double bed, wardrobe and bedside cabinet). have 4 doors which one set has double glazed glass either side of it (quite a large area). So I feel a sealed system would be good. I have been quoted potterton 24KW (which I think would do the job), A Glow Worm 18KW (which I think is too small and after contacting the manufactuer they seemed to agree. I just need some help if you can give it. As I beleive as well that if the boiler is too large then the boiler would not modulate correctly and would cost me more to run the the right size.

Please help from a very confused and frustrated me.

Many Thanks in advance for you info.

 

[rojaca]

if you visit the energy saving trust website you can do an online calculation.
unless your original radiators were oversized then you may struggle to get the necessary heat loss across your htg system to keep your boiler running at its most efficient.

 

[bengasman]

An oversized boiler will not use more than a close match, but will cost more to install.
No point in doing a heat requirement calculation, as your boiler size will be directed by existing rads, unless you are prepared to replace your rads to satisfy your calculation.

The size of your boiler in kW, is the length of all your rads together in metres x 1.25. This is based on a height of 600 and a single panel with fins. Adjust for different heights and double the length for double panel. The first model upwards of the figure you find in the brand of your choice will be the closest match.

 

[Agile]

The boiler should be matched to the house heat loss which you can calculate using the whole house heat loss program.

Oversizing will cause the boiler to short cycle as it will be unable to modulate down to the heat loss required during milder weather.

Also consider Viessmann boilers fitted by one of their approved installers as they have a five year warrantee.

Tony

 

[bengasman]

...Oversizing will cause the boiler to short cycle as it will be unable to modulate down to the heat loss required during milder weather....

Come on Tony, I would expect better from you. Even the 35 kW Viessmann will modulate down to 10 kW, which is the capacity of 5 small/medium rads.