Hot Water Cylinder Size?

[SteamyTea]

4 minutes ago, Nickfromwales said:

pastie-loving opponent

Now that is an idea, a copper water coil in a Cornish Nasty, they can burn the roof of (and off) your mouth many hours after leaving the oven (a McDs apple pie is the same, but smaller).

Sorted, Pasty Power with Cornish Copper.

 

(Phelps in Hayle is the best in the world, just make sure you go to the original place, not the satellite shops)

Edited May 29, 2021 by SteamyTea

[ashthekid]

We have a plant room created big enough probably for 2 slim but tall cylinders. It’s also housing the UFH setup. 
It’s going to be rare for there be any more than the 4 adults & 1 child - i.e guests staying. So demand will be lower than the predicted amount in a 6 bedroom/6 bathroom I would say. 

[Nickfromwales]

1 minute ago, SteamyTea said:

Now that is an idea, a copper water coil in a Cornish Nasty, they can burn the roof of (and off) your mouth many hours after leaving the oven (a McDs apple pie is the same, but smaller).

Sorted, Pasty Power with Cornish Copper.

 

(Phelps in Hayle is the best in the world, just make sure you go to the original place, not the satellite shops)

Is it far from Truro general? I know where that is. Nearly chopped my leg off on a ship in Falmouth dry dock, when looking the wrong way whilst holding a 9” grinder with the trigger held on……

How we laughed. ?

[Nickfromwales]

3 minutes ago, ashthekid said:

We have a plant room created big enough probably for 2 slim but tall cylinders. It’s also housing the UFH setup. 
It’s going to be rare for there be any more than the 4 adults & 1 child - i.e guests staying. So demand will be lower than the predicted amount in a 6 bedroom/6 bathroom I would say. 

Thank you. 
However, you will actually be FAR better off with the single 500 afaic.

With PV you will be able to force feed spare energy into that via immersion(s) so you’re basically paying a few hundred quid more for a big, basic, energy capacitor. 
Don’t fear a 500L uvc, that’s pretty much what I would put money on would best suit your ‘predicament’.  With PV it also provides a runaway lane for excess so 2 birds one stone. 

[Nickfromwales]

UFH can be pushed into a convenient corner. UVC needs priority. That’s how I set out for all of my M&E projects, with priorities appropriated. 

Edited May 29, 2021 by Nickfromwales

[SteamyTea]

1 minute ago, Nickfromwales said:

Is it far from Truro general

No, up to the A30, turn left, 15 miles down the road, turn right at roundabout, after a mile or so the road turns to the left, it is on your right.  Opposite side of the estuary from the old power station, where they were going to build a nuclear one, till they found the background radiation was higher than allowed for a nuclear plant.

That would have killed the property prices in St, Ives.

I had my trousers taken down in Treliske by a nurse, because I had broken my pelvis, about the same time that Samantha Camerone was squeezing another sprog out there.

But don't anyone come down my end of the country while the G7 is on, the security is tight.  Been told that I am possibly going to have to be 'escorted' to work.  They have build two 'villages' that I know of already, and have heard rumours that the road next to mine is where the police cars are going to be based.

[SteamyTea]

17 minutes ago, Nickfromwales said:

24 minutes ago, ashthekid said:

We have a plant room created big enough probably for 2 slim but tall cylinders. It’s also housing the UFH setup. 
It’s going to be rare for there be any more than the 4 adults & 1 child - i.e guests staying. So demand will be lower than the predicted amount in a 6 bedroom/6 bathroom I would say. 

Thank you. 
However, you will actually be FAR better off with the single 500 afaic.

Can you easily fit an immersion heater (powered by the PV) half way up the cylinder, so you can heat the top half i.e. 250 litres, to say 60°C while the ASHP supplies the bottom have at 48°C, and still have a 'stable' system, or would too much turbulence happen?

 

Here is what happens, thermally, inside my cylinder over 24 hours.

 

and I can get two baths and a quick shower or two out of that.

Edited May 29, 2021 by SteamyTea

[dpmiller]

^ that's pretty much what I'm doing with my TS @SteamyTea. HP coil buffers the system/tank to at least heating flow temp, but can raise the whole tank to DHW temps if the upper/lower immersions haven't done that using the PV.

[Nick Laslett]

9 hours ago, SteamyTea said:

Can you easily fit an immersion heater (powered by the PV) half way up the cylinder, so you can heat the top half i.e. 250 litres, to say 60°C while the ASHP supplies the bottom have at 48°C, and still have a 'stable' system, or would too much turbulence happen?

 

Here is what happens, thermally, inside my cylinder over 24 hours.

 

and I can get two baths and a quick shower or two out of that.

Just asked in another thread about the theory about immersion placement. Surely at the bottom to give fully use to solar divert is better?

[SteamyTea]

42 minutes ago, Nick Laslett said:

Just asked in another thread about the theory about immersion placement. Surely at the bottom to give fully use to solar divert is better?

As I am on Economy 7, I have two elements. The main one at the bottom 'that heats the whole cylinder' and one inserted at the top that heats about a third of the cylinder.

But as my chart shows, the base of the cylinder us pretty close to the incoming water temperature. So assuming once the cylinder has settled the median temperature is a lot lower.  That lower temperature settled at about 30⁰C.

But the top third if the cylinder is over 40⁰C.

 

The point I am making is regardless of the set temperature, the actual usable water is a lot less. But still adequate.

 

I assume that you currently all live in a house together, take some measurements. Water flow, duration and temperature.

Do this for a week or two and see what you actually use. By taking the guesswork out you can make a much better decision.

[PeterW]

45 minutes ago, Nick Laslett said:

Just asked in another thread about the theory about immersion placement. Surely at the bottom to give fully use to solar divert is better?

better to use a dual immersion and dual control immersion diverter to get stratification in the tank. Heat the top to 75°C on the primary divert load immersion then drop to the secondary so you significantly increase the available water when blended down 

 

With a  large PV install,  a 500 litre UVC is the way to go - certainly provide the bulk of any hot water needs in the summer.  

[fezster]

Soem UVC manufacturers have 40KW+ coils (eg. Joule High Gain). With DHW priority, you could get away with a smaller cylinder which heats up rapidly to keep up with demand.

[Andehh]

Just to update the thread when we originally assumed 500L for 6 bedrooms (3 bathrooms)....now settled on 300L with ASHP. The higher heat loss & actual need for that volume of hot water just didn't make sense for us to go for 500L. It is a constant high thermal loss & enhanced strain on ASHP to keep it hot....for a volume of water we would use <5% of the time. 300L should cover our needs for 90% of the time, so a reasonable medium ground of cost/efficiency/need.