Heating and DHW for large Barn.

[cadbury]

Hi,
I need to work out a system for a 5 bed ,4 en suite plus family bathroom
barn conversion.3 people live there. I worry about the cost of running a large cylinder to provide DHW. Would it be simpler to have 2 combis (oil)
and split the house in to 2 zones? Then have electric showers.

I have seen a system with a thermal store where the dhw is provided from a heat exchanger.Can a heat exchanger cope with long runs to taps ?

Thanks in advance for any help.

 

[picasso]

Is this for yourself or are you speccing for a customer ?

 

[cadbury]

its for myself.

 

[dcawkwell]

Unvented ACV cylinder it can heat as you use it.
If this is a true barn conversion it may be that you don't have the
water supply to run 4 on suites at once though so an accumulator tank
might be advisable if you have good pressure say 2.5 bar.

 

[cadbury]

Thank you, I will check water supply though it seems good. Its a 6" main down to 25mm pipe, (20m) I will check flow.

 

[xr4x4]

Just go for a large, or two unvented cylinders.

They don't take that long to reheat.

Keep it simple.

 

[picasso]

What you trying to achieve ? rolls royce , budget or middle ground ? how often are the bathrooms going to be used at the same time, what type of heating you got , under floor , rads ?

 

[cadbury]

Middle ground. I will have rads. I would say 2 bathrooms used at the same time but not that often. They could be 20 m apart if that makes any odds ?

 

[cadbury]

Thank you, I will check water supply though it seems good. Its a 6" main down to 25mm pipe, (20m) I will check flow.

I'm getting 55 L a minute out of a 22mm pipe.

 

[MJGas]

Thank you, I will check water supply though it seems good. Its a 6" main down to 25mm pipe, (20m) I will check flow.

I'm getting 55 L a minute out of a 22mm pipe.

 

[cadbury]

Any thoughts on a twin combi system ? What about a thermal store with heat exchanger for dhw ? Thanks.

 

[AngelesPlumbing]

I know its your house but the law states to fit unvented system you must have G3 qualification. Its your decision to get competent person or got trouble selling your house or bomb in your home

 

[cadbury]

I know its your house but the law states to fit unvented system you must have G3 qualification. Its your decision to get competent person or got trouble selling your house or bomb in your home

Thank you. I will get a suitably qualified person to do the work.
It would be helpful to have a varied opinion on my double combi idea or im happy to take advice from experienced people with different ideas of what would be the most cost effective long term solution.

 

[muggles]

Electric showers are pants, even the good ones, and if you have four 10.8kw showers turned on at the same time your meter will be spinning so fast it'll fall off the wall. Either that or everything will stop - it's a 180 amp draw which your domestic supply wouldn't actually cope with.

Two combis will still be two combis, the flow rate out of each isn't going to be fantastic, although it is better than gas as they contain a small store of water that's continually kept at a higher temperature then blended down, and relative to an unvented cylinder their heat loss is quite high

A thermal store still requires you to keep a large volume of water hot, you're just keeping the primary water hot rather than the domestic hot water. No real benefit other than not needing G3 to fit it

Your best option is still unvented IMHO. Go for something with a high heat recovery, and maybe a twin coil so you can just keep the top bit warm all day and heat the rest when you know you're going to need more hot water.

 

[dhutch]

Mate of mines parents recently had two combi is there large and rambling town house replaced with a single combi and, i think, an unvented cylinder. They where replacing old with new, but apparently logistics of having two combi's, servicing, etc, didnt work out for them, and they have seen a significant cost saving this winter.

I have a Main 30 HE in my house, which is the first time I have lived with a combi rather than a unvented cylinder (parents house is elec only eco7, immersion and underfloor night store, due to no gas and not wanting oil) and while it can do a cracking good shower, its not as good as the one at my parents, and clearly using the full lot. Turn a hot tap on and it goes cold, shower at 3am when the pressures up a bit and you have to turn flow down slightly for it get to full temp.
Also, it takes twice as long to come through hot if you just want to wash your hands, or do a single dish. If your doing a load of washing and want to rinse stuff, the short on-off cycle leads to it going cold and you have to wait again for it to come through warm.

Not a plumber, but for me, stored every time.

Get a nice big cylinder, enough for when the kids bring back a group of 8 people who have just been biking and are muddy, wet through, can becoming cold! As long as its well insulated the losses are small, and doubling the volume only marginally increases the surface area!


Daniel