Solar Thermal Install

[Onoff]

but if you added another cylinder with the option of being tank fed

that system would heat that tank up then be cooled by the cold water tank fed from the tank above

or feed the extra water into a hot tub therefore cooling the cylinder down that can be either an ibc tank homemade hot tub but not used for that as its just more of a cooling tank of water

That's food for a mad thought...I figure I'm amongst like minds!

I've the lounge diner from Hell. Ostensibly two separate rooms for now. The diner is the very original house. It's 9" solid brick with a suspended timber floor over dirt. The lounge, a later addition is 9" block wall. Neither the ceiling, walls or floor line up between the two rooms.

Plan is to knock through at some stage. The lounge floor is interesting. 5/8" chipboard (yes, honestly). 4x2 joists. A dwarf brick wall, one brick high, then a concrete slab. If anyone's seen The Money Pit, I did once sink through the carpet. Where I went through:

Quick repair:

They got the levels wrong so there's a slope up from the diner into the lounge.

Found a plan of the ground floor I did a while back. The red is the single pipe central heating system:

How about, when I dig out the lounge floor I bury one or more, heavily insulated water tanks as a thermal store?

 

[knighty]

how much hot water do you use?

honestly... best advice is to keep it simple

and cheap, no point spending more than it'll save you?

 

[Onoff]

how much hot water do you use?

honestly... best advice is to keep it simple

and cheap, no point spending more than it'll save you?

Daughter lives in the shower / bath. If there's copious hot water they'll user it. Dumping heat to the hot tub is certainly an option. Or garage even.

 

[voipio]

What happens when the glycol boils? Does this get taken up by the expansion tank?

Yes. But the expansion tank pressure needs to be adjusted to work properly as an expansion tank. The system described above had the expansion tank precharged to 3 Bar, the same as the safety valve, so when the system boiled, it vented itself through the safety valve, and the pressure became vacuum when it cooled. It stopped working because of lack of fluid and gaps in the fluid (vacuum locks, as opposed to airlocks). The system needed refilling using a thermal transfer fluid charging pump to get it working again.

 

[gaz1]

hot tubs are a good size 1000 gallons so there a good source of heat dump when your solar power is too much for your system

its better than boiling your glycol for it to release on pressure

so add something cheap to build and holds alot of water ibc tanks hold alot of water and still there a good source to dump heated water into for the same thing

 

[Onoff]

hot tubs are a good size 1000 gallons so there a good source of heat dump when your solar power is too much for your system

its better than boiling your glycol for it to release on pressure

so add something cheap to build and holds alot of water ibc tanks hold alot of water and still there a good source to dump heated water into for the same thing

We do have one of the inflatable Lazy Spas. One kid used it for a year or so, now it's forgotten about. It sits under an overhang on the SE corner of the house.

It was a nice spot for the table and to have a beer. SWMBO decided otherwise.

Heat store, some body figures so

Bit of a Sun trap tbh. Allegedly this bit was glazed in years ago. I did wonder about doing the same. Insulate the floor and just pipe off hot air from this "hot box" to the rest of the house.

 

[Onoff]

I even once though of re-laying the patio where it's a sun trap. Excavate and put down 150 - 300mm of pri/eps. Do an insulated upstand. Then black dyed concrete with a copper or some other gylcol proof slinky in it.

NB: Wear shoes. Worry about small children later.

 

[Edward Teach]

Worry about small children later.

Their leash should hold them back

 

[Onoff]

Well Sevenoaks aint to far from Maidstone so if you want a look let me know.

I might take you up on that! Reminds me I've an invite to go and see a lad in Deal who did his own external wall insulation.

 

[Onoff]

so add something cheap to build and holds alot of water ibc tanks hold alot of water and still there a good source to dump heated water into for the same thing

What's the score with ibc tanks used like this? Insulate them? Place in a dedicated "shed" even? Can't grasp where you would place them, how to stop them freezing etc. That's a lot of water there in winter.

 

[Gareth J]

That's a helluva utility. And the boiler's there already. I'd be considering putting in as big a tank as reasonable in there. Maybe 500l, maybe bigger if funds/space allows. Not cheap though.

My preference would be an open vented cylinder, with a coil in the bottom for the ST(and maybe the heat pump we may be cajoled into getting) and a coil in the top for mains pressure DHW, reducing legionella risk. It'll a be inside the thermal envelope of the house so, in winter, you won't be wasting inefficiency heat. Being open vented, won't require regular inspections. (Though how many people actually get pressurised ones inspected, I don't know)

The lower 1/3-1/2 of the cylinder would be tapped to do the central heating and the boiler would feed into the top of the cylinder. In a situation where the solar tubes get the tank to ~80C, you can circulate the central heating, or, a separate designated rad or towel rail to dump heat somewhere it's useful or at least not annoying.

Set the timer of the boiler to "check" the status of the top of the tank a bit before showers are anticipated and top up the temperature if it's too low.

Incentivise people to shower/bath when the tank is hot! What you don't want to do, whatever your system, is to control the boiler vaguely, let it top the tank up to temperature early in the morning and reduce the "space" for more heat from the panels.

Regarding ibcs, their only bonus is they're cheap. If you were building from scratch, you could consider including a basement of wall to wall ibcs that summertime excess generation dumped heat into, for use into the autumn for space heating. But then, what is their temperature limit...?

 

[knighty]

you don't have enough panels to have vast amounts of spare heat heating up big hot water tanks or thermal stores

I'd fit the panels, plumb them into a 2nd hot water that that goes before the one you already have to act as a pre-heat tank

for a heat dump just put a radiator in the loft, up high above the panels, with a 3 way valve so in a power cut the solar panels will heat the radiator by convection and save the system from boiling

mount the radiator 90' so instead of water in and out at the bottom the inlet is at the top and outlet is at the bottom

 

[Mikes]

you don't have enough panels to have vast amounts of spare heat heating up big hot water tanks or thermal stores

I'd fit the panels, plumb them into a 2nd hot water that that goes before the one you already have to act as a pre-heat tank

for a heat dump just put a radiator in the loft, up high above the panels, with a 3 way valve so in a power cut the solar panels will heat the radiator by convection and save the system from boiling

mount the radiator 90' so instead of water in and out at the bottom the inlet is at the top and outlet is at the bottom

So on a hot summer day when the cylinder is full of hot water and the solar collectors are still producing heat, you are suggesting dumping the heat into the loft space to make the house even hotter.

 

[gaz1]

What's the score with ibc tanks used like this? Insulate them? Place in a dedicated "shed" even? Can't grasp where you would place them, how to stop them freezing etc. That's a lot of water there in winter.

ref: hot tub

water storage reference: but can be used as hot water storage

heat storage using drums usually found in greenhouses as can be the rear wall of drums but do store heat

 

[voipio]

The boiling of the thermal transfer fluid in the solar panel tubes isn't really an issue, provided the expansion tank is set to the correct pressure in the first place. The panels get hot, and radiate and convect the heat away, and the fluid vapour condenses in the cooler parts of the system, so the expansion tank has to deal with, at worst, about 1 to 2 litres of fluid per panel. The propylene glycol will degrade a bit faster under these conditions but, in the UK at least, there tends not be that many full on clear sky days in a year. It does seem a bit of a waste, throwing away nature's bounty, though.

 

[gaz1]

Incentivise people to shower/bath when the tank is hot! What you don't want to do, whatever your system, is to control the boiler vaguely, let it top the tank up to temperature early in the morning and reduce the "space" for more heat from the panels.

Regarding ibcs, their only bonus is they're cheap. If you were building from scratch, you could consider including a basement of wall to wall ibcs that summertime excess generation dumped heat into, for use into the autumn for space heating. But then, what is their temperature limit...?

ibc tank is really an expansion tank in the loft a rather large one

it can store heat just like passive wall storage in greenhouses like the barrels

but with plastic it can fail with heat and cold

they are rather cheap to get started on until you save up or buy a better tank

30.00 vs 500.00 or even 1000.00 depending on the tank that you choose

the advantages they store on top of one another
there cheap to buy
as long as fit them with a breather there fine to use as hot water expands the above video gives reference to both stacking and overlfow reference, but dosnt have the breather pipe on them if fitted with water

there great for off grid applications for both water collection or heat storage

fit them into walls of r28 or more you have a good heat store

 

[not done it yet]

So on a hot summer day when the cylinder is full of hot water and the solar collectors are still producing heat, you are suggesting dumping the heat into the loft space to make the house even hotter.

The roof space is hot anyway. It is just to lose extra heat on some days of the year. Heat rises - and there should be at least 300mm of insulation on the roof ‘floor’ to prevent heat loss from the habitable parts of the dwelling.

I simply conclude you are wrong.

 

[gaz1]

also you can store ibc on pallet racking so only needs 4 concrete base pads



worried about water spilage from a bust ibc tank



as you can create a shed for it that means you can insulate the shed well

 

[Gareth J]

A quick Google suggests IBC rating is about 60C. ST panels could happily boil water. For a bulk, low temperature store, great. But needs failsafes to be sure that they can't get too hot if something accidentally got left in the wrong setting while away on holiday for example. If you're limited to under 60C, that's a bit cool as a preheater for tap water but not useless. Could be more useful for space heating but even then, better in a well insulated house with low temperature emmiters/UFH. For most people, where it's going to be retrofitted and space is at a premium, you can maximize kWh/m3 by simply raising the temperature.

 

[Onoff]

I would not under any circumstances consider putting ibc tanks in the loft. Ground space I have plenty of.

I think I'd rather divert excess to storage for night time, space heating release.

Looking at my plan above...I could bring the kitchen out to encompass that current covered space. I could then hive off the back of the kitchen for a plant room. It'd be nominally dead centre of the house so losses would be internal.