Hot Water Cylinder Questions
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2. There is no reason (space permitting) why you can't install a hot water cylinder (be it direct, indirect or thermal store), and use the radiator-heating bit of the combi boiler to heat the water in the cylinder just like you would do with a standard non-combi boiler. This isn't trivial, and needs the appropriate controls, but certainly do-able.
Presumably you could treat the cylinder as a second zone in the same way that you can control the heating in different parts of the house with more sophisticated controls.3. As long as the cylinder has an electric immersion heater (whether it's a bog-standard internal one or NI-style Willis heater that goes on the outside) you can then heat your water with a combination of gas, surplus PV or paid for electricity, whatever you choose.
Subject, I presume, to the proviso that you don't want an immersion heater that draws more power than your PV can provide.
It was helpful to me.Hopefully there's something here that helps someone, MikeReed0 -
Slightly off-topic but why don't people like unvented water cylinders? I had one installed in my old house in 1998 and it gave me excellent mains pressure hot water, enabling me to get rid of a very noisy power-shower pump. I did not have it serviced for 20 years until I noticed water from the overflow pipe. Another advantage was that I didn't have to worry about the tank in my loft getting too cold in winter because I no longer had one. The only downside was that it took up more space in my airing cupboard and was so well insulated that the airing cupboard was no longer got significantly warmer than the rest of the house.Reed0
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HiReed_Richards wrote: »... Subject, I presume, to the proviso that you don't want an immersion heater that draws more power than your PV can provide ...
That's what the term 'proportional' in proportional diversion devices tends to cover .... a 3kW immersion can be operated as a variable power device with control being fully proportional to excess PV generation!
HTH
Z"We are what we repeatedly do, excellence then is not an act, but a habit. " ...... Aristotle
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Reed_Richards wrote: »Slightly off-topic but why don't people like unvented water cylinders?
Hi - I had one in my last house and thought it was a very good option. The advantages (to me) of the thermal store this time round were:
1. DIY install - because it is not pressurised it's inherently safer and can be legally installed yourself - this was my main reason for doing it, saved me several hundred pounds in installation costs.
2. No need for annual servicing (not sure if people actually do this but it is recommended).
3. The store I bought stores the water at 75 degrees and then mixes it with cold as it is used to bring the temperature down to 50 degrees. This means more energy storage capacity. No reason I can think of why you couldn't do this with an unvented cylinder, but not and out the box solution in this configuration.
So I wouldn't say that I don't like unvented cylinders, it's just that for me the thermal store had all the advantages and more - anyone else want to comment?0 -
It's not just 'recommended' - it's mandated. Ignore at your own peril.2. No need for annual servicing (not sure if people actually do this but it is recommended).
anyone else want to comment?
Should the unvented cylinder ever blow up (unlikely but not unheard of) insurers will want to see the servicing record before they will consider paying out the claim.NE Derbyshire.4kWp S Facing 17.5deg slope (dormer roof).24kWh of Pylontech batteries with Lux controller BEV : Hyundai Ioniq50 -
My unvented cylinder had a small expansion vessel that sat on top of it. My boiler had the same thing. I would have thought if anything was going to blow up it would be this expansion vessel.Should the unvented cylinder ever blow up (unlikely but not unheard of) insurers will want to see the servicing record before they will consider paying out the claim.
In which case the one on the cylinder, being inside a cupboard, would probably do less damage than the one atop the boiler.Reed0 -
Don't you mean "stores the water at 75 degrees, uses that to heat a cold infill via heat exchange and then mixes the output with more cold to bring the temperature down"? Or have I misunderstood how these things work?3. The store I bought stores the water at 75 degrees and then mixes it with cold as it is used to bring the temperature down to 50 degrees.
By the way, can you monitor the temperature in the cylinder or do you have to take it on trust?Reed0 -
Reed_Richards wrote: »Don't you mean "stores the water at 75 degrees, uses that to heat a cold infill via heat exchange and then mixes the output with more cold to bring the temperature down"? Or have I misunderstood how these things work?
By the way, can you monitor the temperature in the cylinder or do you have to take it on trust?
Hi - yes, you're absolutely right, my wording was careless - whoops!
The thermal store I have has a dial thermometer pushed into a special boss in the cylinder, which shows the temperature towards the top of the cylinder.
By way of a further update on how this is working:
1. I've been doing some testing and found that in my installation, once the thermal store is up to 75 degrees it will give me sufficient water for normal use, including good hot showers in the evening, without any more heating for 2 days.
2. I can't really quantify this yet, but my instinct is that I'm losing quite a lot through standing heat losses, both as a result of the lagging of the adjacent pipework and controls, and as a consequence of running the cylinder at quite a high temperature. I'm going to continue to experiment a bit, starting by running it at 60 degrees or so for a week or so and see what effect that has. Once I've done that, I'll lag the pipes better and see what difference that makes.0 -
You may well be right. But are you happy to take the risk of finding your house is uninsured ? If you are, then you can make an even bigger saving by cancelling any house insurance policy you might haveReed_Richards wrote: »
My unvented cylinder had a small expansion vessel that sat on top of it. My boiler had the same thing. I would have thought if anything was going to blow up it would be this expansion vessel.Originally Posted by EricMears
Should the unvented cylinder ever blow up (unlikely but not unheard of) insurers will want to see the servicing record before they will consider paying out the claim.
In which case the one on the cylinder, being inside a cupboard, would probably do less damage than the one atop the boiler.NE Derbyshire.4kWp S Facing 17.5deg slope (dormer roof).24kWh of Pylontech batteries with Lux controller BEV : Hyundai Ioniq50 -
You may well be right. But are you happy to take the risk of finding your house is uninsured ? If you are, then you can make an even bigger saving by cancelling any house insurance policy you might have
There are plenty of youtube clips that demonstrate what can happen..
https://www.youtube.com/watch?v=iIm6JXQQ8kw4kWp (black/black) - Sofar Inverter - SSE(141°) - 30° pitch - North LincsInstalled June 2013 - PVGIS = 3400Sofar ME3000SP Inverter & 5 x Pylontech US2000B Plus & 3 x US2000C Batteries - 19.2kWh0
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