External Boiler 18m from house?

[Bemak]

Hi all, 

 

In the initial throws of a refurb at the moment and one thing I'm trying to bottom out is the location of the external boiler. The existing house doesn't really have a rear elevation - it's seen on all sides which is making it a bit difficult to locate the best place for the boiler (inside is not an option). 

 

I have a shed nearby that would be perfect, but it's 18m from the house. I appreciate that this is quite a distance, but just wondering if I did a deep trench for the pipework and double up on the insulation around the pipes themselves, would it be a viable solution?

 

Just wondering if anyone else has located their boiler a similar distance from their house and what they did to minimise heat loss. 

 

 

[Marvin]

I have not done this. However I wouldn't do this. Pipes in trenches in the ground are a big heat loss thing especially over that distance.  Yes it can be done but you will be paying a lot more for heating and hot water forever...

 

I saw one once. The concrete path above the pipes melted the snow, and the rain water flowing around the pipes absorbed heat before flowing away.  It would have been better to lay them in a swimming pool.

 

Outside temperature effects ground temperature significantly in the first meter so on very cold days the ground around the pipes will be colder...  Protecting boiler and pipes from freezing will be achieved by running the boiler during the day and night or antifreeze??

 

Humidity effects the electrical side of a boiler and components. 

 

I wouldn't do this either, but it would be better off in the loft if you have one suitable. 

 

The best place is inside the building thermal envelope. 

 

Other's may have other opinions

 

Good luck

 

M

 

[Temp]

Any room in the loft?

[JohnMo]

1 hour ago, Bemak said:

if anyone else has located their boiler a similar distance

Our heat pump is about that distance, I trenched about 600mm. Insulated pipes in 25mm black insulation, then aluminium foil tape wrapped and then inserted into 110mm Flexi underground twin skin pipe. Sealed the ends at ground level with stainless steel mesh and spray foam (stop mice etc).

 

Zero issues.

[ProDave]

1 hour ago, Bemak said:

The existing house doesn't really have a rear elevation - it's seen on all sides which is making it a bit difficult to locate the best place for the boiler (inside is not an option). 

Is there some local rule that says a boiler cannot be seen?  If not just choose the least viewed elevation and put it there?

[Nickfromwales]

Is this an oil boiler? If so, these can live outdoors without issue. 
 

For pipe work, see: https://www.watts.eu/en-gb/products/eu/microflex-pre-insulated-piping/pipes-for-heating/1-microflex-uno-6-bar

 

If you are left with zero other option then I’d use one for flow and another for return, to take full advantage of maximum insulation per application. 25mm will suffice unless it’s a big house with a load of radiators where you may need to jump up to 32mm.

 

As said, the best place is indoors, but it is what it is. If this is a home form,I’ve then I’d dig a big trench, and make an EPS coffin for the pipes, but defo not burying DIY insulated pipes as water ingress will cost you big over time. The Watts kit comes with weathertight cap ends which you can seal up with CT1 to keep the pipes bone dry. 

[Bemak]

56 minutes ago, ProDave said:

Is there some local rule that says a boiler cannot be seen?  If not just choose the least viewed elevation and put it there?

its a personal preference to not see it. 

[Bemak]

35 minutes ago, Nickfromwales said:

Is this an oil boiler? If so, these can live outdoors without issue. 
 

For pipe work, see: https://www.watts.eu/en-gb/products/eu/microflex-pre-insulated-piping/pipes-for-heating/1-microflex-uno-6-bar

 

If you are left with zero other option then I’d use one for flow and another for return, to take full advantage of maximum insulation per application. 25mm will suffice unless it’s a big house with a load of radiators where you may need to jump up to 32mm.

 

As said, the best place is indoors, but it is what it is. If this is a home form,I’ve then I’d dig a big trench, and make an EPS coffin for the pipes, but defo not burying DIY insulated pipes as water ingress will cost you big over time. The Watts kit comes with weathertight cap ends which you can seal up with CT1 to keep the pipes bone dry. 

 

yes I was looking at something similar. An extra bit of lining in the trench like you say will help a lot. 

[Nickfromwales]

30 minutes ago, Bemak said:

 

yes I was looking at something similar. An extra bit of lining in the trench like you say will help a lot. 

Yup. A bit of sweat and endeavour will drop the losses a lot vs just dumping the pipe in the ground. 
 

Look to dig a bit deeper and to possibly have the trench fall away from the boiler, with a layer of 150mm or more of pea shingle to sit the pipes and insulation on to. If the run is flat, just fill a decent sized sump in the middle of the run as a soak away.
 

The pea gravel will allow water to soak away from the pipe etc, as water will be the enemy here for heat loss. 

 

Use sharp sand to bury the pipes and insulation, then backfill with the excavated muck. Allow for the muck away of the unwanted (excess) spoil. 

[Bemak]

that's a great point regarding the soak away in the middle of the run. Thanks Nick!

[G and J]

6 hours ago, JohnMo said:

Our heat pump is about that distance, I trenched about 600mm. Insulated pipes in 25mm black insulation, then aluminium foil tape wrapped and then inserted into 110mm Flexi underground twin skin pipe. Sealed the ends at ground level with stainless steel mesh and spray foam (stop mice etc).

 

Zero issues.

That’s good to hear as we have a remote heat pump.   Did you do the pipes that way to save cost re the pre-insulated ones?

[JohnMo]

47 minutes ago, G and J said:

That’s good to hear as we have a remote heat pump.   Did you do the pipes that way to save cost re the pre-insulated ones?

Had the 110mm stuff already in my left over build pile. But refused to pay a small fortune for pipes that had worse insulation than I wanted. So 28mm Hep2O roll, several lengths of closed cell insulation and aluminium tape left over from build. And an hour or less of my time. No special coupling needed either just normal Hep2O ones. All in less than a 1/3 the price for materials and no delivery charges either.

[G and J]

4 hours ago, JohnMo said:

Had the 110mm stuff already in my left over build pile. But refused to pay a small fortune for pipes that had worse insulation than I wanted. So 28mm Hep2O roll, several lengths of closed cell insulation and aluminium tape left over from build. And an hour or less of my time. No special coupling needed either just normal Hep2O ones. All in less than a 1/3 the price for materials and no delivery charges either.

Coincidentally, I found out today that I needed circa 15m of twin wall 110mm ducting and on my first Google it looks like the min I can order is 50m.  Plus I could replace those pipes if I had a failure. I think you may have saved a fair bit of money for us!  Thank you.