HW run to garden room 30m in buried pipe? Shall I?

[gasjunkie]

Hot water run to garden room 30m in buried pipe? Shall I?

Hi guys I'm putting in a garden room like the rest of the country and about to dig a trench for the drain and services...

The garden room will have an occasional use shower, sink and WC. I'm reluctant to install an electric water heater &/or electric shower because of the space it will take up. The convenience (I realise there will be a little wait) of having HW directly from the house without any gear to go wrong is certainly tempting.

The trench will run across the lawn 16m and along the side of the house (another 16m).

I have an extension going in soon so I am tempted to put CW supply and insulated HW 22mm in the trench were it can punch back into the cellar where the boiler and incoming mains CW are located. Combined distance lawn (16m) + along side of house (16m) is around 32m.

The garden room is around 16m from the back of the house (once the extension is built) so another option is to take the HW from the the shorter distanced point, around 16m.

Be great to hear any thoughts on the run, is 33m ok for example , any advice - in particular what type/brand of pipe for the HW.

Cheers in advance.

 

[ShaunCorbs]

Sorry to say you can’t as it’s a wastage of water before it gets hot

Little under sink water heater is the only option

 

[king of pipes]

Have to agree you will need to go Electric. Regards kop

 

[gasjunkie]

Sorry to say you can’t as it’s a wastage of water before it gets hot

Little under sink water heater is the only option

Thx Shaun, when you say 'can't'... can you pls elaborate ?

 

[Ric2013]

Water Regulations. 30 seconds to get to 50 degrees at tap. Otherwise it's considered a waste of (hot) water to drain off the dead-leg. Bit stupid really, as you could have a tap that runs at a million litres per minute and then you'd fit in the 30 second bracket nicely.

I'm sure you could put in secondary recirculation if you have a hot water cylinder (plus perhaps a pneumatic switch to action the pump on the odd occasion you are actually in the 'garden room', but additional cost (double the pipework) and a pump required.

If you're running underground, forget half-hard copper and forget the push-fit systems - these are not designed for underground use. Don't think MDPE is designed for hot water. Soft copper and (I'm pretty sure), galvanised steel can be used underground. But check manufacturers' specifications for suitability as I'm not an authority on this.

I hope this gives you some inkling why you electric is likely to be the way forward...

 

[ShaunCorbs]

Yep it’s water regs as ric says

 

[gasjunkie]

ok thx that helps to understand....

a secondary return loop is a good option as I have a cylinder + secondary return loop in the house already.

There are pre-insulated pipes for running underground to outbuildings (or when say a boiler is in an out building) eg Polypipe:

Pre-Insulated Pipes & Fittings

Highly flexible, pre-insulated piping system, combining both the flow and the return medium pipes in the same jacket pipe, primarily intended for the transport of heating water or other heat-transfer media in underground distribution networks. The medium pipes are made from cross-linked PE-Xa...

www.polypipe.com

They do a twin pipe so I could lay that easily in one hit and there's my loop.

So that might be best option and I can avoid electric

 

[ShaunCorbs]

That’s acceptable but you won’t have change out of 1k

 

[Chuck]

I suggest you calculate the cost of the losses you're going to experience before finally deciding. Your pipes are going to be relatively small, which means the surface area and hence losses are going to be large relative to the capacity of the pipe.

Also, be careful about how you 'punch back into the cellar'. You don't want to find your cellar gradually filling with groundwater getting in through your hole.

 

[Murdoch]

If you go electric be careful to discuss your requirements fully with a spark so the cable is the correct size !

 

[gasjunkie]

ok so an update to this -

I have now run twin pre-insulated 22mm pipes (buteline) in the trench out to the garden room, buried in trunking. I have a cylinder + secondary return loop in the house already.

Shall I create a second circuit with a separate pump and possibly a flow activated switched pump
or
do I connect to existing loop ?

grateful for views on best way to connect.

 

[ShaunCorbs]

Be easier and cheaper long run to install a cylinder in the garden room

Would need its own loop and run back to the cylinder

And I would use another pump and put a switch in the garden room which would turn the pump on so who ever is using the room when they get in there flick the switch and by the time they’ve sorted themselves they would have hot water

 

[gasjunkie]

Be easier and cheaper long run to install a cylinder in the garden room

Would need its own loop and run back to the cylinder

And I would use another pump and put a switch in the garden room which would turn the pump on so who ever is using the room when they get in there flick the switch and by the time they’ve sorted themselves they would have hot water

thx Shaun but no room for a cylinder (in the garden room)