For one reason or another I have to have a new water tank. The existing one is in an airing cupboard in the bathroom which SWMBO would like to get rid of at some point. It has no immersion heating which I would specify on the next one, to enable me to better use excess solar power and also maybe use my cheaper rate electricity to heat water instead of expensive gas. (I could bodge turning on immersions when the sun is bright or buy one of the purpose built devices for a few hundred).
So it would probably make sense to put the new tank up in the loft.
Looks like there are a number of options but I'm thinking I would probably like an indirect unvented, one of those which delivers your hot water at mains pressure thereby doing away with the shower pump. I don't mind spending a few bob on it but I don't believe I was a Rolls Royce solution.
Any opinions or recommendations welcome!!
|
>>instead of expensive gas.
I thought gas was and still is cheaper than electricity.
Our heating and hot water is all gas and when I get our hot water tank replaced it will have an electric immersion heater as a standby.
We are looking at getting a pressurised system (from mains cold water) and get rid of the header tanks in the loft.
I think the most efficient way to heat water using solar is to actually run the water through black pipes on a south facing roof. I have been surprised at noticing steam on a black surface that I have in the garden which had a few puddles on it in late March / April turning to steam in the morning sun (at one point there was so much that for a moment I thought it might be on fire).
|
|
I can see how solar thermal could be very effective. I have am anthracite garage door that faces SW. This afternoon it is too hot to keep my hand on it.
|
My south facing roof is already covered with solar panels. And it's not that big anyway.
They are generating electricity I am not using, and the spare could drive an immersion, then whatever other fuel source I need it would use less.
I don't know how you actually compare relative cost of elec v. gas when heating water but if I were to heat at my overnight rate it would be 5p per kWh (will be 7.5p from end June).
And my home grown electricity is a lot cleaner than gas :-)
|
With solar panels you have five options:
- use the electricity as it is generated,
- sell it back to the grid (prices vary but ~5p per kwh)
- store it - but this involves buying batteries (lots of investment cost)
- use it to heat hot water cylinder (cheaper for of storage than batteries)
- waste it
So although per KWh gas is cheaper than electricity - using surplus generation to heat domestic hot water may be the best of the alternatives.
|
Hmmm well an over-the-wall chat with my plumber has indicated that the unvented indirect cylinder could (= will usually) cost getting on for £2.5k by the time I've had pipework moved around, possible accumulator, new shower pump etc etc.
Replacing what I have already like-for-like would be under £1k, but if SWMBO gets her way with the bathroom we'd be doing the bigger job in the not so distant future anyway. So I'm feeling at the moment that's what I'll go with, but happy to keep receiving thoughts.
Either way it presents me the opportunity to do something about using the excess solar.
I'm not sure batteries would be much over £3k for a modest array but given I HAVE to do something with the water anyway the batteries are kicked into the long grass.
|
Treated SWMBO to an outing to Wickes and Homebase this morning to suss out what sort of thing she is thinking of, bath-wise.
She has come round to my way of thinking, a walk-in shower is preferable.
So we will be doing the like-for-like replacement of the existing cylinder which keep the cost down a lot, as (for instance) we'd have needed a new shower on top of all the other bits, and when the time comes to change the bathroom the shower gubbins will require less structural change than the bath being moved around (and the hardware will probably cost less too).
Takes away any servicing in the loft issue. I think they main downside is not having hot water at mains pressure, but I've coped all these years...
|
>>>downside is not having hot water at mains pressure<<<
The money you have saved, put in a pump for the shower. Nothing beats a good high pressure feed to the shower.
|
I've had an Aqualisa Quartz for years now, it provides a really good pumped shower, nicely thermostatically controlled so you get no sudden blasts of hot or cold. Ive had to replace the controller unit once.
I'm feeling that the whole bathroom refit may now happen this year. We won't have to replace the Aqualisa (£800+) which will be another saving - though sod's law says it will fail not long after it's moved... Still the more modern version is WiFi connected so I can make a rule on the Home Assistant that if anyone other than me spends more than 5 minutes in the shower the water starts to cool :-)
|
Tank and 27" thermostat ready for collection tomorrow @ Toolstation. Around £225 after £25 money off voucher. Plumber will supply other fitting and pipe etc. Maybe two days to install?? I can't imagine the bill reaching £1k.
The Solar iBoost (if I do that) will be about £320 I think plus a bit for fitting
Last edited by: smokie on Sun 15 May 22 at 17:06
|
Have you got a Surrey or Essex flange installed ?
While you have a plumber onsite - worth doing ?
I would have one installed but I think my old cylinder would collapse if disturbed.
|
I have no idea, I'm in Berkshire if that helps :-)
Will Google it now...
|
|
Do not forget the flange or Google will probably extoll the good life in Surrey.
|
As an ex Viz reader, I was concerned what Google might show me when I searched for flanges.
However I am now expert on them if anyone needs to know anything.
I can categorically state I have no idea if I have one, but have mailed my plumber to ensure he knows about them :-) (He is also my next door neighbour, and is a Gas Safe, Corgi etc registered plumber of many years)!)
|
My next door neighbour is a real flange....I;ll ask him. Oh, hang on, we've not spoken for 3 or 4 years !
Ted
|
I think the most efficient way to heat water using solar is to actually run
>> the water through black pipes on a south facing roof. I have been surprised at
>> noticing steam on a black surface that I have in the garden which had a
>> few puddles on it in late March / April turning to steam in the morning
>> sun (at one point there was so much that for a moment I thought it
>> might be on fire).
>>
I've seen a few of those, I think they are good idea if you don't have much roof space. So i'm led to believe anyway.
|
|
When I looked at them years ago, they were quite expensive and the govt grant was considerably less, which is why I filled my roof with solar electricity panels. No idea of prices now but it does seem a good idea, for hot days at least. OTOH maybe it has been somewhat superseded by heat pump systems (which I'm gathering are quite expensive and may well require considerably changes to existing pipework and can be noisy and quite expensive to run)
|
>> I have been surprised at
>> noticing steam on a black surface that I have in the garden which had a
>> few puddles on it in late March / April turning to steam in the morning
>> sun (at one point there was so much that for a moment I thought it
>> might be on fire).
That's NOT steam, it's water vapour and quite normal as the water heats up and evaporates, then quickly turns back to visible water vapour.
|
The UK unvented hot water cylinders are expensive and in the UK require a specially (pressure vessel?) qualified plumber to install, and are subject to Building Control. They are also required to be serviced annually.
In france everybody has unvented tanks with pressure relief valves and are sold at low cost in all the building DIY outlets. I have never seen press stories about people suffering from scalding or shrapnel wounds when they finally expire. Several builders I know have imported them into the UK as a low cost solution for flat conversions.
If you install in the loft, be wary of maintenance plumbers who will refuse to service it unless the access hatch etc and roof space are fully protected. I know somebody who had problems when his pet plumber installed ch boiler was refused maintenance under warranty by the manufacturers approved maintainers.
|
|
Is there a big price difference between the UK and France, how much are we talking?
|
A 200L cylinder can be bought from about £200 inc fittings but the price can double for bigger name brands. If you require larger cylinders the price can go up quickly. But it is possible to install 2 cylinders if your occupancy warrants it.
www.bricoman.fr/chauffe-eau-vertical-blinde-no-name-200l-1316175.html If you page down to the bottom of the web page you will find other manufactures competing products.
Other info - (if your french is upto it)
www.leroymerlin.fr/comment-choisir/comment-choisir-son-chauffe-eau-electrique-a-accumulation.html
You may like to read this.....
www.easyflow.co.uk/G3-building-regulations.html#:~:text=In%20fact%2C%20the%20revised%20G3,to%20comply%20with%20Part%20P.
|
>> If you install in the loft, be wary of maintenance plumbers who will refuse to
>> service it unless the access hatch etc and roof space are fully protected. I know
>> somebody who had problems when his pet plumber installed ch boiler was refused maintenance under
>> warranty by the manufacturers approved maintainers.
I can confirm that.
My parents had a condensing boiler in the loft and when it became faulty the company providing the annual maintenance contract refused to touch it unless the loft floor was boarded, there was a permanent loft ladder, there were rails around the loft hatch and if the loft wasn't fully boarded, rails on either side of the path to the boiler.
A few other independent plumbers moaned and groaned so in the end they got a new boiler installed in the garage.
|
|
again in same position. the immersion uses 4 kw i think the solar panels are producing . what 2 at very best. iam thinking heat pump and under floor water pipes are the end game
|
I have enough historical 30 minute data on usage (and solar production for past two years) that I should be able to knock up a spreadsheet to see if it's really worth doing for the solar side. With only a modest array my spare isn't massive but with gas prices appearing to be on a one way trip at the moment who knows?
I still think I am probably near a point where I can use my 4 hours of cheap overnight electricity to heat water though. I've not yet found a decent way to compare cost v. gas though
|
> I've not yet found a decent
>> way to compare cost v. gas though
>>
Isn't it a matter of how much gas vs electricity you need to raise the temp to blah degrees to blah degrees in your tank?
|
>Isn't it a matter of how much gas vs electricity you need to raise the
>temp to blah degrees to blah degrees in your tank?
It is, but the awkward bit is working out the losses for each energy source. An immersion heater should be more efficient than a gas boiler with associated pipework but might be more expensive because of the difference in kWh cost.
www.car4play.com/forum/post/index.htm?v=e&t=26824&m=586576
|
|
3+ years ago, I'm impressed.
|
"Isn't it a matter of how much gas vs electricity..."
That's what I thought too Sooty but it doesn't seem as simple as that.
However someone elsewhere has more or less said that electricity is 100% efficient while gas it probably only 75% at best. So given my unit cost for gas and electricity will be virtually identical over 4 hours per day, electricity should work out cheaper. (Right now my cheap electricity period is only about 2/3rds the cost of gas!!)
It seems the only way will be to get the new tank, all fitted out with immersion heaters top and bottom, and try each combination.
Last edited by: smokie on Sun 15 May 22 at 01:07
|
Have you thought of switching to a heat bank cylinder instead?
One of the best moves we made was using one of these as it stores the energy longer, gives you mains hot water and allows multiple inputs (solar thermal, wood burning stove and gas, immersion, and even a heat pump) I have all of those without the heat pump. It also buffers the gas heating supply and ensures the return to the gas boiler is at the correct temperature to ensure it is operating in condensing mode all the time. Because the water temperature within it is stratified it also supplies the underfloor heating with water already at the correct temperature.
I thought of adding a heat pump but the cost isn’t worth it as grants only really apply if you are single supply of electricity with no gas. A cheap heat pump is around 2k plus fitting and with a gas bill of about £600 pa it will never really pay off.
Incidentally I also have one of those solar diverter things for excess solar electric. I got a cheap £100 thyristor based one off eBay.
You need the thyristor one as it gradually shunts excess power into the immersion in proportion to the excess energy that would go to the grid.
It’s not so useful now we have batteries installed that take any excess solar, but even these sometimes reach 100% charge and so the excess might as well be used. We have an automation that charges the car above 97% battery charge but the car is sometimes not there or is fully charged.
|
I don't think I'm wrong in saying that my plumber has made himself one of these, based around a cast off cylinder from a job he was on and some electronics provided by a friend.
He didn't suggest I should have one, and it sounds rather complex and, more to the point, expensive than I am looking for. Not least because this whole episode is a distress purchase to fix a problem rather than a planned re-working of my technology... :-)
Last edited by: smokie on Sun 15 May 22 at 19:10
|
>> this whole episode is a de-stress purchase
So retail therapy then? ;-)
.. and next time someone asks me what I'm doing when I have just ripped the guts out of a project I will tell them I am doing a "planned re-working".
|
|
I've just had a new condensing boiler and rads fitted in my new place. It seems I got what may be the last boiler (Ideal) in the locality. I hear Worcester-Bosch are in serious trouble and can't produce boilers, due to lack of chips and may be laying off staff.
|
|
Have you considered a phase-change battery? Electrical heating only but equivalent heat capacity to a hot water cylinder in a quarter of the space, and more efficient.
Last edited by: Fursty Ferret on Tue 17 May 22 at 08:34
|
It can only be more efficient because the heat loss is typically lower (or negative?)?
A big tank is a thermal battery. And you can heat it with gas/direct electric/heat pump/solar.
You just need a place to put the big, well insulated tank.
|
Yes, but if you leave a hot water tank overnight it gets cold and in the summer warms your house up needlessly. Typically associated with gas or oil heating as opposed to electric, but if you're replacing it anyway you can reclaim some cupboard space.
Admittedly a bog-standard tank with an immersion heater linked to the panels will probably be cheaper in the medium term.
|
Which is what I'm going for.
I've also found that in theory it will be cheaper for me to heat the tank using my 4hr cheap electricity rather than gas, according to some, as the unit price is about the same but efficiency of elec is greater. At least till the electricity goes up again!!
|
|
Thermal stores like our one are very well insulated though and with no demand on them would stay warm a few days. They are big by necessity. Ours is around 500L.
|
Well the new cylinder is fitted, not without problems, but that seems par for the course for most things I get done these days.
The lingering problem is the Aqualisa shower - having spent quite some time getting it to run at all airlock, reset required, none of which were obvious or well documented) it seems I may have an open circuit to the socket in the loft which it plugs in to.
Symptoms are live being supplied to socket (if I take the face plate off I can get a reading on my mains testing screwdriver) but nothing plugged in works. Have I reached the right conclusion?
Having said that I need to speak to my plumber as I can't see where the immersion is switched.
|
>> Symptoms are live being supplied to socket (if I take the face plate off I
>> can get a reading on my mains testing screwdriver) but nothing plugged in works. Have
>> I reached the right conclusion?
Live supply but neutral side open?
|
Replacing a hot water cylinder - zippy
