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2-1/4" BSP to 1 1/4" BSP reducer? (For 12V immersion heater).

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490808
Posts: 1487
Joined: Mon Jul 19, 2021 1:10 pm

2-1/4" BSP to 1 1/4" BSP reducer? (For 12V immersion heater).

#1

Post by 490808 »

One of my future solar projects includes trying to use a 12 V immersion heater to heat hot water.

Yeh I know its a dumb idea but I've been thinking about it for so long that I really want to try it.

So what I intend to do is fit a Willis type water heater to one of our hot water tanks and put a 12 V immersion heater in the Willis case rather than the normal 220 V element it normally has.

For those that have never come across a Willis heater dismantled it looks like this ...

Image

and its fitted like this ...

Image

If its a complete failure then I can always use it as intended with the proper 220 V element.

The reason I have some hope that is will work is that the Willis heater is used when you only want to heat a small amount of water. They are normally used with a timer and 10 minutes of heating should heat enough water at the top of the tank for a quick shower. Saves heated the whole tank with a traditional element. So provided the 12 V heater heats the water enough to start the thermosiphon action then it should heat the water at the top of the tank? I'm thinking of using a 400W 12 V element. The heating would only be required in the summer when the wood burner isn't heating the water.

NOW HERE'S MY PROBLEM .....

The Willis takes a short 11 inch long immersion heater with a standard 2-1/4" BSp fitting but all the 12 V immersions are either 1 inch or 1-1/4 inch BSP so I need a reducer. Yes I can buy one on ebay but I including delivery and import duties that will set me back £55 (more than 65 euro at current exchange rates) and would be the single most expensive part of the project. I'll probably just spend the money but I haven't given up on a cheaper solution yet.
kadman
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Posts: 2759
Joined: Tue Jul 20, 2021 6:14 pm

Re: 2-1/4" BSP to 1 1/4" BSP reducer? (For 12V immersion heater).

#2

Post by kadman »

I cant see how that circuit will work. How can you have the heated water from the element entering the top of the tank, where you have hot water normally rising in the tank and exiting there?
490808
Posts: 1487
Joined: Mon Jul 19, 2021 1:10 pm

Re: 2-1/4" BSP to 1 1/4" BSP reducer? (For 12V immersion heater).

#3

Post by 490808 »

Works perfectly well. Hot water rises displacing cold water out the bottom of the tank creating a thermosiphon.

Same way the water in the direct hot water boiler in our range gets hot and heats water in the hot water tank.

You don't have to have pump to move water around provided you have a heat differential. Ideally you want your heat source low down compared to the tank to get the best heat differential but with correct pipe sizing you can get it to work with them at the same level. The diagram is about right because you normally use a Willis heater to heat a small amount of water at the top of the tank rather than the whole tank.

About the only place that uses Willis heaters seems to be Northern Ireland, no idea why?
kadman
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Posts: 2759
Joined: Tue Jul 20, 2021 6:14 pm

Re: 2-1/4" BSP to 1 1/4" BSP reducer? (For 12V immersion heater).

#4

Post by kadman »

I thought direct hot water systems were long gone.
490808
Posts: 1487
Joined: Mon Jul 19, 2021 1:10 pm

Re: 2-1/4" BSP to 1 1/4" BSP reducer? (For 12V immersion heater).

#5

Post by 490808 »

I put one in because I wanted a simple system that works when there are power cuts. Its nothing more than a tank connected to a boiler by two lengths of copper pipe. There are plenty of solid fuel systems installed by "plumbers" that have to be put out when there is a power cut. Even an indirect system shouldn't need a pump for hot water but most can't work without one.
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