Best way to run hot water from boiler to shower 20m away

[reallybrokendav]

Hi,


I'm looking for some advice. We are in the doing an extension on the side of a bungalow. The (oil-fired) boiler is currently against an internal wall in the kitchen but will be moved to a newly formed utility room. Once this is done the kitchen sink will be about 6m away from the boiler, the main bathroom 7m away and a new ensuite will be 20m away from the boiler.


So I appreciate that there will be a bit of a wait when I turn the shower on in the morning! Someone I spoke to suggested a secondary return for the hot water - based on a timer - to offset the distance issue.


We currently have a gravity-fed hot water tank. We are considering putting in a "megaflow" tank. Since we're in a bungalow we can put it in the loft so another option would be put the tank in the middle of the house so that there's less cold water in the pipes before the hot water arrives (as an alternative to a secondary return) I appreciate that there would be some heat loss on the pipes between the boiler and the water tank but presume that it wouldn't be much if they are properly lagged.


Given the location of the boiler and the bathrooms etc.. is one option better than the other or is it just a trade-off?


I'd like to use the most efficient method - both costwise and also in terms of wasting as little water as possible.


All comments welcome!




thanks.
Dave

 

[SimonG]

Unvented in middle of house, closest to use of majority of hot water.

 

[reallybrokendav]

Unvented in middle of house, closest to use of majority of hot water.

Thanks Simon. So you don't rate secondary return? It seemed like a good way to reduce the amount of water wasted waiting for the water to heat up.

One thing I realised that I've neglected to mention, I've measured the flow rate at 15l/min via a 15mm copper pipe. I'm with Thames Water and they were unable to tell me what the flow rate / pressure was in the street so I also need to somehow ensure that I've got a decent enough flow rate / pressure for an unvented system.

 

[SimonG]

You would need your static and dynamic pressures and flow rates. Might need to upgrade incoming main or fit accumulator or break tank and booster.

 

[reallybrokendav]

thanks again - I guess I can get a decent plumber to find that out for me?

So if unvented isn't an option would a gravity-fed tank in the middle of the house (close to majority use of hot water) still be the best solution?

 

[SimonG]

Yes as long as you have enough height over the tank for cwcs.

 

[reallybrokendav]

Actually thinking about it, if it's gravity fed than the tank will need to be on the ground floor as it'll need a header tank in the loft to provide the pressure. I think we'd look at a shower pump for this scenario to ensure that there's ample pressure to the shower.

As a non-techie the secondary return sounds like a good idea - why isn't it something that you'd recommend?

 

[Best]

Ideally you don't want secondary return unless you have to.
Cost of extra pipework, plus a secondary pump, but also heat loss to be considered.
Basically, - average homes - keep it simple.

 

[reallybrokendav]

thanks - it just seemed that 20 metres was a long way away. Although actually if it goes in the middle of the house than it's only 12m away