Pipework from Existing Boiler to New Outbuilding

[fixitflav]

So in that case the only choice I have is either get a gas pipe pulled and have a combi boiler or all electric?

No, you have several choices

1. Stick with your original plan to pipe hot water across the garden, but use an insulated pipe bigger than 15mm.
2. Put a combi boiler in the new building
3. Put a heat-only boiler in the new building
4. Put a system boiler in the new building
5. Go all electric

 

[ripperuk]

No, you have several choices

1. Stick with your original plan to pipe hot water across the garden, but use an insulated pipe bigger than 15mm.
2. Put a combi boiler in the new building
3. Put a heat-only boiler in the new building
4. Put a system boiler in the new building
5. Go all electric

Thanks very much for breaking the choices down. I assume for No.1, I use 22mm?

For No's 2,3,4 I would need to feed a new gas pipe, so I guess I would need to decide whether to take a copper pipe safely or get the gas company to extend their existing pipe to the new building.

No.5 is the easiest, but also expensive in the long-run due to the high prices of electricity.

 

[Harry Bloomfield]

No.5 is the easiest, but also expensive in the long-run due to the high prices of electricity.

All of those options, will cost a considerable amount to install. As I suggested earlier, have you looked at diesel heaters? Cheap to buy, reasonable to run, quick and easy to install. You feed them diesel/kerosene/heating oil, you have a small combustion air intake, an exhaust out (outdoors), unit indoors, has an air input, and a blown hot air output.

 

[fixitflav]

I assume for No.1, I use 22mm?

I suppose so, but I haven't worked it out. Somebody mentioned insulated pipe, which you'd need.

For No's 2,3,4 I would need to feed a new gas pipe, so I guess I would need to decide whether to take a copper pipe safely or get the gas company to extend their existing pipe to the new building.

I'm a DIYer but I doubt copper is best choice for a buried pipe, I assume it would need protection from corrosion. Yellow PE as used by Cadent etc is the obvious choice, cheaper and comes on a roll so no joints.
If the new boiler is 15kW, it uses about 1.4m3/h gas, and for 20m length 20mm ID I make pressure drop < 0.5mb, meeting regs.

 

[endecotp]

high prices of electricity.

Has anyone suggested air source heat pump yet? I.e. one of the air-to-air, reverse-aircon, type units?

 

[Harry Bloomfield]

Has anyone suggested air source heat pump yet? I.e. one of the air-to-air, reverse-aircon, type units?

Yep, me #19...

Would an air source heat pump make it worthwhile?

Another idea, might be a diesel heater, they are cheap to buy, cheap to run, I use one rated 8Kw, to heat my workshop. The size of a shoe box, they suck room air in one end, blow hot air out the other, you just need to keep the tank filled with diesel, or heating oil (kero).

I would suggest that making use of the existing boiler, to supply heat along 20m + 20m flow and return, is a none starter. The delays, and heat loss along the pipe, unless extreme measures were taken with insulation, would be silly.