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Electric shower, anything I can do?

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richard.cs:

--- Quote from: paulca on July 24, 2019, 01:04:14 pm ---Can you elaborate a little?

I was considering going for the System boiler approach which has just a hot water circuit flowing through the heat exchanger coil in the hot tank, which, assuming I fit an electrical routing valve giving me control of hot water only, radiators only and both gives me the best of all worlds.

--- End quote ---

System boiler plus storage tank is essentially what you have now, only at the moment you have a low pressure storage tank and you're proposing a high pressure one. This is often a good system as you get mains pressure hot water without the downsides of a combi boiler. It's not a very common approach in the UK mainly because of historical inertia I think but there is not a lot wrong with it. You can generally expect it to behave like a mains pressure version of your current system. Disadvantages over low pressure tank are generally that it's normally a smaller tank holding less hot water and that the tank lasts less long (they're coated steel rather than copper so they corrode out). If your household tends to have baths rather than showers you might prefer a low pressure system (little else has the ability to fill a bath of hot water as quickly as a header tank and large-bore pipes), if your household is small and hot water usage is max one shower at a time then a combi might be better than either storage approach.

Storage (either kind) also gives you free electric backup (immersion heater) and gives you some future options for solar heating.

richard.cs:

--- Quote from: paulca on July 24, 2019, 01:19:09 pm ---Is this a mainland thing?  I have lived in about 5 different places in Northern Ireland with vented/pumped heating systems and there has only ever been one control, heating on, heating off.  If it's on, you get both hotwater and radiators, if it's off you get neither.

--- End quote ---
Maybe it is. I have lived in four places in the South of England, all had low pressure hot water systems with a choice of hot water only or hot water plus heating. All of my friend's and family's houses are either like this, have a choice of all three, or have combi boilers.

paulca:

--- Quote from: richard.cs on July 24, 2019, 01:21:07 pm ---System boiler plus storage tank is essentially what you have now, only at the moment you have a low pressure storage tank and you're proposing a high pressure one. This is often a good system as you get mains pressure hot water without the downsides of a combi boiler. It's not a very common approach in the UK mainly because of historical inertia I think but there is not a lot wrong with it. You can generally expect it to behave like a mains pressure version of your current system. Disadvantages over low pressure tank are generally that it's normally a smaller tank holding less hot water and that the tank lasts less long (they're coated steel rather than copper so they corrode out). If your household tends to have baths rather than showers you might prefer a low pressure system (little else has the ability to fill a bath of hot water as quickly as a header tank and large-bore pipes), if your household is small and hot water usage is max one shower at a time then a combi might be better than either storage approach.

Storage (either kind) also gives you free electric backup (immersion heater) and gives you some future options for solar heating.

--- End quote ---

Thanks Richard, this confirms my thoughts.  I expect the conversion plumbing will be easier going to high pressure storage "System boiler" than combi anyway.  And I am interested later in attaching a DC immersion from a solar panel.

richard.cs:

--- Quote from: paulca on July 24, 2019, 01:26:15 pm ---And I am interested later in attaching a DC immersion from a solar panel.

--- End quote ---
The one to watch there is the thermostat. They won't survive switching DC so an external contactor or similar is needed.

If you have a plastic header tank you also need to have a high-reliability way of ensuring you never boil the tank.* Standard (modern) immersion thermostats have a second set of contacts which fire at about 90 C and are not self-reseting to get double fault to danger, you need to replicate that level of safety so a single contactor driven by the thermostat isn't really good enough.


*There have been a couple of scary incidents in which stuck immersion contacts have boiled the storage tank, forcing circulation into the roof tank until it too is filled with very hot water. The plastic tank then gives way pouring 100 gallons of near-boiling water onto the poor sod asleep below.

soldar:
Every country has its own culture in everything, including solutions to common technical problems. It is interesting to see this as you live in different countries.

In Spain gas water boilers (heaters) have a combined system where they can heat the house radiators and the domestic hot water. In the summer you can have domestic hot water without heating the house. The thought that you either do both or none seems rather crazy to me. If you want domestic hot water you need to heat the house? How crazy is that?  What's the point?

Still, these combined gas heaters are complicated and expensive and when they break down everything goes down.

I like to have independent systems as much as I can and as simple as possible. But people love the idea of saving a little space and having a compact gadget that does five things although it does them all badly.

A friend of mine bought a combined scanner-printer against my advice. Shortly after the printer stopped working and I got a free scanner.

People love buying a laptop computer because they "don't have the space". Then they bitch when the smallest thing breaks and it is too expensive to repair. Or when they can't install that card or whatever.

People love the apparent simplicity and later find out things do not work so well.

For simplicity, low cost and reliable service it is hard to beat the American system of having a domestic hot water tank separate from the house heating. 

I always bitch about this to my friends. In Spain you can go to a really expensive, luxurious home but you can't take a comfortable shower there because water temperature is wildly unstable. WTF? What kind of luxury is that? I'd rather live in a shack with a good shower.

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