Boiler energy efficiency

Joined
12 Nov 2010
Messages
136
Reaction score
3
Country
United Kingdom
My heating engineer is about to install the CH boiler (second fix to new build which is predominantly UFH)
The choice of boiler is either oil or LPG fuel (no natural gas & discounted ASHP)
He says that oil is the cheaper option because apart from the cost of the oil the boiler operation is better controlled by the room stats rather than a LPG boiler modulating down as the returning flow water temp dictates.
Which theory holds up for UFH??
Thanks
 
Sponsored Links
You clearly have some doubts about this guy's expertise? Maybe worth asking a couple of others what they'd recommend? Individual installers often have preferences based on their own idiosyncrasies rather than carefully deciding what is best for each customer. Maybe your engineer isn't even certified to install LPG?

I think most people would say that a modulating boiler is overall more efficient, or at least not less efficient. It is considered desirable for a boiler to be able to operate continuously, or at least for long periods, rather than turning on and off. This is done by properly sizing the boiler and if possible by choosing one that can modulate down enough to run more or less continuously. Domestic oil-fired boilers generally don't modulate at all and so oil boiler sellers like to manipulate the numbers to suggest that modulating boilers are a lot less efficient.

Probably far more important would be the cost of the fuel, and possibly of the installation itself. LPG is generally more expensive, although there's no guarantee that will always be true. Oil boilers are usually very slightly more efficient than LPG boilers, all other things being equal, but you'd be hard pressed to see the difference. Have you looked into fuel suppliers for your area?

I'm not sure if any of this changes for UFH. Other than running at a relatively low flow temperature, the boiler doesn't really know what type of heating system it is attached to.
 
Sponsored Links
The engineer is installing a Grant 45kW boiler (600 mt sq floor area) but the problem I have is the thought of that size boiler satisfying one room in the house whereas a modulating boiler would turn down to around 8kW thus running longer.
 
think of a modulating boiler as the accelerator pedal on your car, when it starts from cold it is flat out and will gradually reduce the amount of gas being used as the return temperatures get higher, and will get to a stage when it is just ticking over and using very little gas just to keep the home warm, an oil boiler will fire , stop fire stop constantly when there is a demand for heat, I know which system I would use but it is your choice
 
The engineer is installing a Grant 45kW boiler (600 mt sq floor area) but the problem I have is the thought of that size boiler satisfying one room in the house whereas a modulating boiler would turn down to around 8kW thus running longer.
600m²? What is it - a mini stately home?

How did the engineer arrive at 45kW, did he do a heat loss calculation?
 
Seems a pretty good assessment of the likely UFH power required!
 
I do love high fuel efficiencies and if it was mine might have a heat pump with a small LPG boiler for peak demands only, just running off a pair of 47 kg cylinders as that will be minimal capital cost.
 

DIYnot Local

Staff member

If you need to find a tradesperson to get your job done, please try our local search below, or if you are doing it yourself you can find suppliers local to you.

Select the supplier or trade you require, enter your location to begin your search.


Are you a trade or supplier? You can create your listing free at DIYnot Local

 
Sponsored Links
Back
Top