Saving money on hot water

[centralscot]

Whilst slightly tangential, I think most people are interested in easy ways to reduce energy costs, as tougher times and higher energy costs ahead seem to be a certainty.

Thinking about reducing my energy bills I was thinking about ways to reduce the amount of energy used to heat my hot water, this should work for people who have a water tank, rather than a combi boiler.

Water tanks are very wasteful on energy, and the amount of water heated bears no relation to the usage.

I discovered tankless inline electric water heaters, which provide on demand hot water.

This can be added to my water system without disturbing my hot water tank. It should mean I would not use hardly any heating oil in summer.

This of course does not help energy independence but as I said earlier give me a good way to conserve my heating oil and save money for a very modest investment.

I will let you know how it works

[KalPrep]

Good idea, I went the oppostite way. We have solar installed and in order to reduce the gas bill, we turned the gas boiler way down and the electric heater in the tank way up then set the water to heat up during the day, when the solar is being most effective (usual 'omg solar sucks in bad weather' caveat applies before anyone starts ) and I therefore make best use of the generated electricity and reduce the gas used. Seems to work so far, we also did the same in terms of using the electric oven and microwave more than the gas hob.

[centralscot]

Kalprep,

I am attracted to solar for heating my water. I would prefer to heat water through tubes as it would be more efficient than pV. Although I am a little worried about the water freezing in the winter. Luckily the inline water heater does not interfere with those plans and would still be useful supplemement to water heating.
I am stuggling to understand your comment about turning the electic heater up ? is your system PV or system which heats water through glass tubes ?

[the-gnole]

You shouldn't run the water that you are using through the pipes, you need a heat exchanger to make it work properly, and a lot more besides.

I'd look at it in a slightly different way if using it directly from the pipe to the tap.

[KalPrep]

I have 4KW of PV installed. The main issue with the newish system I have is that it uses a whole heap of gas to get the water up to temp. However we have a very good tank with an adjustable electric heater coil to keep the tank at a good temp. We had a problem early on when we moved in that the hot water was way too hot, even when we dropped the gas boiler right down and reduced the time it was enabled on the controller.

When we called a friend he told us to check the heater coil setting and it was that which was really high. Now it works in our favour as we set the hot water to come 'on' during the day and with the gas boiler turned right down and the heater coil right up, it uses more electric (which is being generated by the panels usually) thus saving us money as we are using the 'free' electric rather than paying for more gas.

We have to be frugal on showers etc otherwise you can run out of hot water

In terms of the tubes, they are generally sealed tubes which heat one set of water and that in turn runs through a coil in a preheat tank which preheats the water before it goes into your boiler, reducing the amount of gas/electric you use to get the hot water to temp.

[the-gnole]

We have to be frugal on showers etc otherwise you can run out of hot water

What size cylinder are you using KP? A lot of the solar cylinders are bigger than normal 36" X 18" cylinders and use twin heat exchanger coils inside to use on both solar and on a heating boiler.

[KalPrep]

It's a standard tank, no modifications. With 4 in the house, hot water is a valuable commodity, kids are young yet but I can imagine bartering coming into the KP household soon enough

[the-gnole]

Sounds like you need a fast recovery HW system, Have you thought about popping another immersion heater in to run off the electric and another Primary coil to come off the boiler heating system?

[centralscot]

4KW Sounds like an impressive PV system. I could not afford something like that, way too many higher priority demands on my cash. I think in terms of bang per buck heating water through a system based on glass tubes would be best. Although if money were no object then an large PV system is better as all the energy is in the form of electricity and therefore more flexiable.

I was not really thinking of heating the water directly, I think about disconnecting my boiler heating coil and route it through a solar panel. The water cylinder would become my heat exchanger. If I measure the temperature of the water in the panel, and in the cylinder, if the panel is higher by a margin of say 5 degrees then enable the pump.

I expect I need antifreeze in the coil circuit. The new inline heater would only make up any shortfall in the required water heating.

I should like to also have a few PV panels so some of the energy is in the form of electicity, I would consider making my own panels ( need to read up) but not immediately, but fencing/Hedging roof repairs a polytunnel and more raised beds have a higher priority.

I hope to do at least some small scale solar experiments in the not too distant future.

Next rainy weekend will probably be time to start the water heater installation.

[the-gnole]

I was not really thinking of heating the water directly, I think about disconnecting my boiler heating coil and route it through a solar panel. The water cylinder would become my heat exchanger. If I measure the temperature of the water in the panel, and in the cylinder, if the panel is higher by a margin of say 5 degrees then enable the pump.

How about putting a second heating coil into the cylinder you already have?

A sidewinder or there is the type that goes into an immersion heater boss.

coil.png (78.49 KiB) Viewed 2708 times