Am I on the right lines?

[james6770]

I'm lucky(!) enough to be moving into a large old timber framed house which needs quite a lot of updating . The central heating seems to be in fairly good condition and has a Boulter Pathfinder oil boiler (45Kw), TRVs on radiators but a hot water tank about as far away from the boiler as could possibly be.

My plans are to update the boiler to gas (available just outside but not taken up by the current owners), re-position the boiler and hot water together in the central area of the house and re-do bathrooms.

I intend to get professional help doing this but as I have an engineering background I like to at least get involved in the decision making discussions.

I have done a heat calc with the Stelrad Start program which tells me that my heat loss is at the 33Kw level before a hot water load. My first reaction was this was a little low but maybe it is right. I was expecting higher.

My view is to put in a new gas boiler (Atag 51Kw?) and a (big) pressured hot water supply - possibly with an accumualtor to support it but I have not had a chance to look at pressure and flow rate yet. I do know that the water main rises just where I want to locate the plant.

Does this seem like the thinking is along the right lines? Any help and constructive opinions are appreciated.

 

[leakydave]

Why fit a 51kW boiler when you only need 36kW (33+3)?

 

[Ray84]

why not get a pair of smaller output boilers (one for smaller side of house and HW) other for larger living area and have the system installed so that if one boiler fails the other can operate the side of the system thats failed?
an accumulator might not be necessary best to get a plumber to check in the early stages

Ray[/i]

 

[Agile]

I have done a heat calc with the Stelrad Start program which tells me that my heat loss is at the 33Kw level before a hot water load. My first reaction was this was a little low but maybe it is right. I was expecting higher.

My view is to put in a new gas boiler (Atag 51Kw?) and a (big) pressured hot water supply - possibly with an accumualtor to support it but I have not had a chance to look at pressure and flow rate yet. I do know that the water main rises just where I want to locate the plant.

With that madness I think you would be better getting a professional to design the system and you could stick to digging the trench for the new gas pipe. At least you could not cock that up ( much ).

Presumably you have budgeted for about £4000-£5000 gas bill each year?

Tony

 

[james6770]

Many apologies. I forgot to add the line that said I had got a figure of 46Kw when I used the whole house sizing method. Sorry, it all looked way out.

That is why I found the Stars number a bit low and have checked that I used the same u-values for the same elements of the model.

I'm looking at the higher number as this feels more "right" as it is a 6 bedroom house with about as much energy efficiency as could be mustered in the 17th Century with a bit of early 20th century additions.

From my lurking in these forums I see the Atag boilers seem to be well regarded and I was wondering what others I might consider in this size bracket.

I'll probably do a full model by hand given the huge differences between the methods.