Huge building heating help

[gravyminer]

Still nowhere to put a log store....

I'm looking at recoup shower trays. Anyone know how much they are? The retrofit version is 275 quid, which is a long payback time.

The water system is basically lots of small houses. I have 8 cylinders. Mains water is boosted and feeding 3x 450 litre accumulators at 5 bar. This then feeds unvented cylinders in each area.

I am quite concerned....

5 bar hot feed to unvented cylinders !!!

 What kind of cylinders are they ?
 And the 450 litre accumulators ?

I have done pressure fed hot water cylinders using reduced mains pressure and a safety blow off valve but never at this kind of pressure.

[Iain]

Hi

I have 8 cylinders. Mains water is boosted and feeding 3x 450 litre accumulators at 5 bar. This then feeds unvented cylinders in each area.

I am quite concerned....

5 bar hot feed to unvented cylinders !!!

 What kind of cylinders are they ?
 And the 450 litre accumulators ?

I have done pressure fed hot water cylinders using reduced mains pressure and a safety blow off valve but never at this kind of pressure.

Unless each Unvented has a pressure reducer on its inlet. Most, if not all are supplied with a 3 bar reducer and safety valve.
If they all have their own reducer, 5 Bar would be fine feeding them, just like mains pressure feeding a single unvented.

Iain

[dhaslam]

Individual pellet stoves could be practical in reception rooms.   They only need to be filled once per day and are usually
easier to install  than woodstoves.    They modulate to room temperature.

[ringi]

Still nowhere to put a log store....

Then where will you store the wood chip?

[pdf27]

Apologies, it's all a bit disjointed again!

• So far as WiFi TRVs go, Honeywell certainly do them, and you can get something similar at Maplin.
• How far do you have to shift the heat? Twin insulated 32mm pipe is available for about £35/metre, and at worst you'd just need to fit a booster pump every 50 metres or so.
• Do you have a part of the building (cellars, nearby barn, etc.) that will be accessible when visitors are there? If not then I think you're going to have real trouble with anything biomass based other than pellets.
• SMA say the same thing as Solaredge about export limitation - did the DNO give you a reason that they didn't permit export-limiting systems?
• With the drainwater heat recovery I was assuming that you could plumb multiple shower units through the same heat recovery unit. The vertical ones go for about £400 each, so if you can get 2-3 through there then the payback time starts getting reasonable. The big benefit in my mind is actually that they effectively double the size of the hot water cylinder - and running out of hot water is something guests will NOT appreciate!
• Why on earth do they need so much storage at such a high pressure? Were they pressure-washing the previous sets of guests?

[guydewdney]

Still nowhere to put a log store....

Then where will you store the wood chip?

Pellets... in a basement room. Pipe in, rather than lug logs. The one that's easiest is 7m3

[guydewdney]

I'm massively improving the water system. It was fortic cylinders in each "apartment". One kitchen literally took 3 seconds from tap opening to ANY water coming out. Then, and I jest not, fifteen minutes for the water to be hot.

The pressure is low. So I'm over pressuring it in the attic, then the flow rates will be improved to each distant point, then a reduction valve to make it sensible.

There's several cylinders at the end of one long run. --------------------P-----b with the round bits being cylinders iyswim

I think I can turn the pump down a bit;-)

[guydewdney]

Pv. We have 'precedent' in that we, next door, have ground mount. So there should be no issue with ground mount pv.  However the dno wasn't happy, as we have 10k of pv, 7 of hydro, and the neighbour has 3 / 3.6 of pv too, all on one tiny transformer (twin pole job, about washing machine size). He mumbled something about harmonics

[pdf27]

Pv. We have 'precedent' in that we, next door, have ground mount. So there should be no issue with ground mount pv.  However the dno wasn't happy, as we have 10k of pv, 7 of hydro, and the neighbour has 3 / 3.6 of pv too, all on one tiny transformer (twin pole job, about washing machine size). He mumbled something about harmonics

Ah - that makes quite a difference: most inverters give a pretty crummy sine wave, and rely on the grid to clean it up, essentially.
What sort of distance are the two places apart? Mostly wondering if there is anything you could do with power you'd otherwise be exporting at the moment.

[guydewdney]

All three properties are fed from one transformer, which is 50m from my house. The big house is 200m from the transformer.

I have two immersuns, feeding my dhw and heating.

Still worth considering a 10kw pv system, and forget the fits?

[knighty]

iirc, you're already using immersions to dump spare power into heat ?   any idea if you have much spare after your water is hot and you don't need any more heat ?

assuming 250m between the properties, it a decent distance but could well be worth sending some power over for heat - you could always stick a transformer at each end so you can run higher voltage between the properties, cable won't be cheap but payback is quick if it saves you a fiver a day ?


as big as possible thermal store would help a lot too, will give you somewhere to store heat while the place is empty ?    - tho I guess with somewhere that big and old it'll have massive thermal mass so you don't really want to let it get cold or it'll take forever to warm up again ?



edit: iird you have 3 phase ?  does the new house have 3 phase too ?  I wonder if there's be any benefit in having the supply to the new place cut off and instead feed it from your supply ? - at least then it would have the benefit of all your generation too ?    gives you a bit more control over use/generation/export and might help swing the dno around to letting you install more solar/whatever

[pdf27]

Hmmm... that's a lot closer than I thought it would be. It's certainly worth looking into whether you can run the heating/hot water off your current metered supply to get the most benefit from the power you're currently exporting.

This does raise another issue though - losses from district heating pipework are about 10-15 W/m at 80°C flow / 60°C return and presumably about half this if you go for a low-ish temperature heat pump solution. I'm not sure on the rules, but would it be possible to put an ASHP/WSHP solution at your current property which heats both properties? The saving from shifting your current heat from electric resistance to heat pump should more than pay for the residual (2kW thermal or so - less than 1kW electric) losses in the district heating pipe. Similar applies to any biomass solution - while your losses go up to ~4kW, it gives you the option of using log or woodchip rather than pellets without disturbing the guests at all, so the fuel cost saving will probably pay for the additional losses. That would also heat your current place, so the power saved from heating could go to plug loads and electric heating in the heard-to-plumb parts of the new place.

[mr_magicfingers]

I can't believe no-one's asked for pictures yet 

Sounds like an amazing project Guy, looking forward to following along and seeing how you manage it.

Can you upgrade the transformer on the pole? When I looked at doing so at the farm, because we couldn't get 3-phase for less than 70k, the cost to upgrade our current 16kva transformer to a 100kva one was £9k. In the end, we didn't go that route and have our 6kw of pv inverter limited to 3.8kw, but for you it might be a worthwhile upgrade if there's enough headroom in the supply.

[todthedog]

Guy
Are you proposing this as a one property either separate and or linked to your own as far as electrics are concerned
Or as refurbished flats to be individually rented?
This would alter your thinking,  maybe even to instant showers and on demand hot water.
Heretical I know!

[guydewdney]

There's a nice picture on Facebook bossington hall

Replying from a phone so excuse shortness

Home is owned by me. Big house by big house ltd. Separate entities.

No way could our supply feed the big house, the incomer is literally the size of my arm. At home it's finger ish size.

We don't intend to keep this forever either so linking stuff isn't really viable.