Retrofitting DC immersion coils for solar dump load

[Tom Richmond]

Hi there, 

 

Is it possible to drill, tap and attach a threaded collar like this: 

... into a calorifier in order to connect a DC immersion element and wire a dump load water heater? 

 

If so:

 

A) Where does one get such a collar? 

B) Is regular silicone good for the job - or should it be high temp? (I think I even have some gasket silicone somewhere...)

C) Any advice or best practice when inserting? How do I avoid existing coils on the inside? I assume best placed low down in the tank? 

 

I have no issues with the electrical side of the install, have done this before a few times but always in cylinders with the threaded insert fitted during manufacture. I worry that the wall thickness would not be sufficient to get a good purchase with the bolts, and that there may be issues of strength when under pressure... 

 

Thanks in advance! 

[Alan de Enfield]

First thought would be that there is not enough thickness.

Where the normal element is fitted there is a big 'boss' built into the tank.

[ditchcrawler]

I think you would need nuts on the inside on those bolts and also a proper gasket to withstand 30 psi + also consider the curve of the cylinder. Maybe this would be a better bet, you could even put an essex flange in for it http://www.reuk.co.uk/wordpress/heating/200w-12v-immersion-heater/#:~:text=A low voltage DC immersion,heat the water most efficiently.

 

dd photo

Edited June 4, 2020 by ditchcrawler
A

[TheBiscuits]

Is this to add a 12V immersion heater to a calorifier that already has a 240V one installed?

 

If so you can get combined 240V & 12V immersion heaters in the one fitting.

 

 

[Jen-in-Wellies]

Not done this myself, but an Essex Flange has been recommended here before for retrofitting a heater boss in to a cauliflower.

 

14 minutes ago, Tom Richmond said:

I assume best placed low down in the tank? 

You assume right!

 

4 minutes ago, TheBiscuits said:

If so you can get combined 240V & 12V immersion heaters in the one fitting.

Probably the easiest solution.

[Tom Richmond]

25 minutes ago, TheBiscuits said:

Is this to add a 12V immersion heater to a calorifier that already has a 240V one installed?

 

If so you can get combined 240V & 12V immersion heaters in the one fitting.

 

 

 

Yes, exactly. The 240v element is still required, but we want to add the 12v one.

 

Any idea where you get a dual element???

[roland elsdon]

9 minutes ago, Tom Richmond said:

 

Yes, exactly. The 240v element is still required, but we want to add the 12v one.

 

Any idea where you get a dual element???

Surecal

[ditchcrawler]

Is that a BSP thread in that adaptor that you have put in your initial posting

[Tracy D'arth]

Not too happy about 240v AC and 12v DC in the same element, I would worry about the risk of insulation breakdown.

Essex flange is easy once you have cut the correct size hole.

[Tom Richmond]

Just now, ditchcrawler said:

Is that a BSP thread in that adaptor that you have put in your initial posting

Not sure, this image (taken from an article on solar dump loads) was just for reference. It would need to be 1" BSP, as that is what most DC water eaters seem to have. 

[ditchcrawler]

Just now, Tracy D'arth said:

Not too happy about 240v AC and 12v DC in the same element, I would worry about the risk of insulation breakdown.

Essex flange is easy once you have cut the correct size hole.

One point to note is that you can get high temperature rubber washers for the Essex flangers, the standard ones wont last long if your engine heats your calorifier and will go hard.

[Tom Richmond]

37 minutes ago, Jen-in-Wellies said:

Not done this myself, but an Essex Flange has been recommended here before for retrofitting a heater boss in to a cauliflower.

OK - I cannot find any dual voltage immersion elements. All my googling turns up are other forum threads with frustrated people looking for this elusive item unsuccessfully!

 

Essex flange looks like a good way to go... Anyone done this? I guess I need to wriggle inside the cylinder with bits of coat hanger or similar in order to attach it? 

[Tracy D'arth]

Essex flanges are fitted from the outside only. They come with a split washer and rubber seal for inside and a wire tool to assemble it all, the fitting and external nut. You do get instructions. Available in lots of sizes.

[Jen-in-Wellies]

15 minutes ago, Tom Richmond said:

guess I need to wriggle inside the cylinder with bits of coat hanger or similar in order to attach it? 

You guess right! Take out the existing immersion heater to get the flange inside.

[ditchcrawler]

12 minutes ago, Tom Richmond said:

OK - I cannot find any dual voltage immersion elements. All my googling turns up are other forum threads with frustrated people looking for this elusive item unsuccessfully!

 

Essex flange looks like a good way to go... Anyone done this? I guess I need to wriggle inside the cylinder with bits of coat hanger or similar in order to attach it? 

I have fitted two Essex flanges in my calorifier, that is how I know about the high temperature rubber washers, if fact I have fitted them twice, once with standard washers and when they leaked with the high temperature ones. Most of the Youtube videos on how to fit them are wrong, you can do it all through the hole you cut in the cylinder, one thing I did do was to flatten the cylinder a bit around the hold as calorifiers are much smaller radious than domestic cylinders.

 

[Tracy D'arth]

Just now, Jen-in-Wellies said:

You guess right! Take out the existing immersion heater to get the flange inside.

No, they fit from outside only!

[Jen-in-Wellies]

Just now, Tracy D'arth said:

No, they fit from outside only!

Goes to show you shouldn't trust YouTube!

[ditchcrawler]

3 minutes ago, Jen-in-Wellies said:

You guess right! Take out the existing immersion heater to get the flange inside.

You dont need to go in via the immersion heater flange

2 minutes ago, Jen-in-Wellies said:

Goes to show you shouldn't trust YouTube!

As I posted their videos are wrong

 

[Tom Richmond]

14 minutes ago, ditchcrawler said:

You dont need to go in via the immersion heater flange

As I posted their videos are wrong

 

This is what their website suggests - but how? What is this witchcraft?

[Onewheeler]

36 minutes ago, Tom Richmond said:

OK - I cannot find any dual voltage immersion elements.

Try typing "dual voltage immersion" into Ebay. Item 293567768276 immediately comes up for 230 / 12 V, others for 230 / 24 V.

[Tracy D'arth]

12 minutes ago, Tom Richmond said:

This is what their website suggests - but how? What is this witchcraft?

There is a brass pipe union flange with 4 "ears" and a split washer and seal which is worked into the tank whilst holding it all together with the wire tool. The ears fit behind the washer and seal. The outside nut screws onto the flange, job done.

Its easier to do than describe, not magic, no witchcraft.

[ditchcrawler]

13 minutes ago, Tom Richmond said:

This is what their website suggests - but how? What is this witchcraft?

Its not whichcraft everything passes through the hole you cut in the tank, The inner flange is shaped to lass though the elongated hole you cut and then can be turned to cover the elongation. The iner wacher is split so that it can be passed through buy winding the edge of the tank through the cut. The rubber washer can be flattened and pushed through. All this is done while being threaded on a piece of string attached to a wire clip that is removed afterwards

1 minute ago, Tracy D'arth said:

There is a brass pipe union flange with 4 "ears" and a split washer and seal which is worked into the tank whilst holding it all together with the wire tool. The ears fit behind the washer and seal. The outside nut screws onto the flange, job done.

Its easier to do than describe, not magic, no witchcraft.

The instructions that come with it are quite explicit. 

[WotEver]

57 minutes ago, Onewheeler said:

Try typing "dual voltage immersion" into Ebay. Item 293567768276 immediately comes up for 230 / 12 V, others for 230 / 24 V.

That item number doesn't appear to exist and all the listings I can see are 24V for the low voltage side.

[ditchcrawler]

6 minutes ago, WotEver said:

That item number doesn't appear to exist and all the listings I can see are 24V for the low voltage side.

I bet that is not CE marked, he admits the thread is slightly out

[Onewheeler]

8 minutes ago, WotEver said:

That item number doesn't appear to exist and all the listings I can see are 24V for the low voltage side.

Blimey, it ended at 17:58! I was looking a few weeks ago for something similar as a conceptual project. I think there were some other suppliers not on Ebay, possibly more kosher. Personally, I'd fit an Essex flange or, perhaps easier, move the existing 230 V heater to an external "Willis" jacket and put a 12V element into the fitted boss. Or the other way round.