Heating recommendation for new building

[Steve Crook]

Hi all,

I'm currently building a new utility room/workshop that's separated from my house by approx 10 Metres. The building is single storey with the following dimensions:
Utility Room: 3150x4900mm
Workshop: 4700x4900mm

Attic trusses provide some additional space above:
Shower Room: 2000x3300mm
Office: 5850x3300mm

Insulation is all to current building regs. i.e. Loads of Xtratherm.

My house uses an oil combi boiler that's badly in need of replacing (and will be) and my plan was been to run pipes underground to the new building. A few people have suggested this is a bad idea and that I should consider a stand-alone solution in my new build. The length of run, time it takes to get hot water through and loss of heat in the pipe all being excellent reasons.

This leaves me with a dilemma of what system to put in my new build. One salesman has recommended electric radiators (Rointe) and an electric water heater. Another thought this was a poor idea and a small oil boiler would be best. A third is suggesting two air-source heat pumps (one up, one down). My only real brief (beyond the obvious need for warmth) is that I get a decent shower, not a warm dribble! Total requirements are:
Hot tap in utility room (other appliances are cold feed only)
Hot tap in shower room basin
Shower
Heated towel rail
Heating of some kind in remaining three rooms

I have no access to mains gas, living in a small village in darkest Cornwall.

Any steers on solutions to consider or avoid would be very much appreciated.

Steve

 

[Davie Jones]

Hi Steve, I think that in terms of running costs a little oil boiler linked to radiators and an unvented cylinder (Assuming the mains pressure and flow is up to it) would be your best bet, you could have an oil combi but I'm not a big fan of them, especially when they go wrong. Another option could be a solid fuel boiler linked to a thermal store, nice in the winter but not always practical if you don't fancy the extra work involved and it can be quite dear to install... Avoid electric unless you have too much money

 

[endecotp]

How often is it used? If it's used infrequently compared to the house, then the economics of running costs vs initial costs change and electric becomes more appealing.

 

[Steve Crook]

How often is it used? If it's used infrequently compared to the house, then the economics of running costs vs initial costs change and electric becomes more appealing.

Apologies, I should have given some indication of that previously. The rooms will be used all day on a daily basis and probably one shower per day.

Electric radiators have a significant initial cost advantage, being about £350 each. If there was no requirement for hot water, I'd probably go for them without further consideration. It would take years to offset the cheaper running costs of more efficient systems. The need for hot water clouds the issue though. Using electric to heat water doesn't feel like a modern-day solution and, I suspect, will be expensive to install and run.

 

[Steve Crook]

Hi Steve, I think that in terms of running costs a little oil boiler linked to radiators and an unvented cylinder (Assuming the mains pressure and flow is up to it) would be your best bet, you could have an oil combi but I'm not a big fan of them, especially when they go wrong. Another option could be a solid fuel boiler linked to a thermal store, nice in the winter but not always practical if you don't fancy the extra work involved and it can be quite dear to install... Avoid electric unless you have too much money

Thanks Davie, that makes good sense to me. My mains pressure and flow are excellent. It solves both the heating and water requirements, the only concern then being install cost and no foresight as to where oil prices are heading in our carbon neutral future!

 

[PullerGas]

Since you're not on Nat Gas Steve, have you considered a stand alone ASHP system for your new build??

 

[endecotp]

One shower per day might be 6 kWh max, which saves you 60p per day = £200/yr using mains gas rather than electric. Not sure what oil costs compared to that.

 

[Steve Crook]

Since you're not on Nat Gas Steve, have you considered a stand alone ASHP system for your new build??

Hi Richard, I'm quite interested in ASHP and would certainly consider it. I've read both good and bad about it (like everything else). My salesman today was advocating ASHP, but a separate unit in each room and only for heating/cooling. This felt very expensive, especially as it still left me needing a hot water solution.

 

[Davie Jones]

Since you're not on Nat Gas Steve, have you considered a stand alone ASHP system for your new build??

Dickie, I'd only go airsource if it would be heating underfloor...

 

[Davie Jones]

Since you're not on Nat Gas Steve, have you considered a stand alone ASHP system for your new build??

Hi Richard, I'm quite interested in ASHP and would certainly consider it. I've read both good and bad about it (like everything else). My salesman today was advocating ASHP, but a separate unit in each room and only for heating/cooling. This felt very expensive, especially as it still left me needing a hot water solution.

Steve, you are mixing your air sources... Your salesman has been selling you air to air heat pumps... Dickie is talking about air to water heat pumps..

 

[PullerGas]

Well, with split invert units it can be both a cheap install & running costs.

http://www.coolequipment.co.uk/air-conditioning

 

[Steve Crook]

Since you're not on Nat Gas Steve, have you considered a stand alone ASHP system for your new build??

Hi Richard, I'm quite interested in ASHP and would certainly consider it. I've read both good and bad about it (like everything else). My salesman today was advocating ASHP, but a separate unit in each room and only for heating/cooling. This felt very expensive, especially as it still left me needing a hot water solution.

Steve, you are mixing your air sources... Your salesman has been selling you air to air heat pumps... Dickie is talking about air to water heat pumps..

Thanks for the clarification Davie. If the ASHP solves both my heating and hot water requirements then it's certainly worthy of consideration. I decided against underfloor heating as, with only two, very well insulated downstairs rooms, I decided a radiator in each would be adequate.

 

[Davie Jones]

Well, with split invert units it can be both a cheap install & running costs.

http://www.coolequipment.co.uk/air-conditioning

Indeed but if they are to be used for heating, then oversize them a tad to allow for the loss in performance when the weather goes cold...Especially freezing fog, the mist forms ice on the evaporator finns and the unit spends a lot of time in defrost..

 

[Davie Jones]

If you are planning to use rads on airsource, then oversize the rads to allow for the cooler water flow from the airsource, I would always recommend a buffer vessel....

Eaton is the chap who is really switched on to air to water.. Not seen him around for a while though.

 

[Steve Crook]

Well, with split invert units it can be both a cheap install & running costs.

http://www.coolequipment.co.uk/air-conditioning

Now that's a seriously attractive website! It appears to solve my heating (and cooling) requirements perfectly and at a reasonable price. With only three rooms to worry about (excluding shower room) it should be quite cost effective. If I could now find a solution to my hot water needs, I'd be delighted.