Thinking of adding an immersion heater to our vertical calorifier

[Simon P]

Thinking of adding 230v immersion element to our vertical calorifier for use when on shore power.

Have fitted a few on shore but never to a calorifier before. What’s the chances the big blanking plug will come out easily or are they prone to corrosion and Im likely to just damage the calorifier?

Any advice would be appreciated. Cheers

Edited May 15, 2024 by Simon P
Add pic

[Tony Brooks]

I would suggest about the same as a domestic one except the calorifier MIGHT be made from thicker copper so may be a little more resistant to damage.

[Simon P]

Thanks Tony. It has a substantial hexagon nut on the blank that I could get a socket on unlike the elements themselves that require those awful box spanners. 

[Tracy D'arth]

Drain it down a bit so that the top is above the water level. Get the plug very hot, with a blow lamp. When it cools it will come undone. If the flange is soldered in, ( unlikely ) don't overdo the heat.

[blackrose]

I removed the boss from mine without a problem (no heat required) and fitted an immersion, but I've heard some can be hard to remove and it's not that difficult to rupture the tank if you're not careful. 

 

I had to find a lump in the insulation on my calorifier and carve the foam off to expose the boss, whereas yours looks like a better quality foam application. Hopefully that might suggest a better quality tank too, although why the builder would install it with the immersion boss at the top of the tank seems odd to me. Where's the PRV - at the bottom? 🤔

Edited May 15, 2024 by blackrose

[Simon P]

Thanks all. Will give it a go soon when the worktop is removed for replacement.

Couldnt get an element in there without the worktop off either.

[MtB]

3 hours ago, Simon P said:

What’s the chances the big blanking plug will come out easily or are they prone to corrosion and Im likely to just damage the calorifier?

 

My thoughts are:

 

1) Being brass plugs screwed into a copper boss they are not prone to corrosion.

 

2) The chances of it coming out are high, but not necessarily that easily.

 

3) Find an accurately-fitting box spanner or 1/2" drive socket for that hexagon, and a balanced T-bar to turn it. Don't try to do it with grips or Stilsons. Devise a way to hold the calorifier properly still whilst applying the loosening torque.

 

4) If it doesn't come loose first proper try, then heat it as Tracy described above.

 

Oh and 5), if you know who fitted it, ask them what sealant (if any) was used on it. Ideally none was used and the seal is a large fibre washer. This should come undone easily. Worst is if they plastered the thead up with Bosswhite and hemp.

[Tracy D'arth]

The flange will be brass sweated/brazed into the copper, hopefully not soldered if it is original to the calorifier and not an addition.

If its been put in with red lead paint and putty you may never get it out!

[David Mack]

3 hours ago, Tracy D'arth said:

Drain it down a bit so that the top is above the water level.

I've read that you should keep the tank completely full to support the relatively thin copper skin while you first try to loosen the plug. Only when it has started to move (and maybe leak around the thread) should you drain the tank to below boss level.

[canals are us?]

when I put an 1.1kw immersion heater in my 1999 built horizontal twin coil calorifier. I bought a deep immersion box spanner and left the calorifier full but the water and pump off. a few taps with hammer to get more leverage and it was loose. have a few towels to hand.  This was 8 years ago. Dreading the day when the calorifier leaks. So expensive to buy.

[Tracy D'arth]

11 minutes ago, David Mack said:

I've read that you should keep the tank completely full to support the relatively thin copper skin while you first try to loosen the plug. Only when it has started to move (and maybe leak around the thread) should you drain the tank to below boss level.

Well if you have to heat it, the water has to be below. The rigidity of the copper is not improved by water, it just adds weight to prevent the calorifier moving.

[MtB]

12 minutes ago, David Mack said:

I've read that you should keep the tank completely full to support the relatively thin copper skin while you first try to loosen the plug. Only when it has started to move (and maybe leak around the thread) should you drain the tank to below boss level.

 

Hard to heat it up much unless you reduce the water level to below the plug. 

 

 

[bizzard]

It has been known, twice here anyway that high up elements in calorifiers can get dry of water and go bang if more than one persons is using hot water, like from taps and showers at the same time., the pump couldn't keep up with the usage. I prefer em horazontal at the bottom of the caly for this reason.   They were x Broads cruisers though with two showers and lots of taps. In their Broads state the have no elements in the Cali cos they're cruised all day long to heat them. But when they're sold off folk tent to put elements in em and this can happen,  Narthen.

Edited May 15, 2024 by bizzard

[Tracy D'arth]

10 minutes ago, bizzard said:

It has been known, twice here anyway that high up elements in calorifiers can get dry of water and go bang if more than one persons is using hot water, like from taps and showers at the same time., the pump couldn't keep up with the usage. I prefer em horazontal at the bottom of the caly for this reason.

I cannot understand how; when a calorifier fills from the bottom and empties from the top; this could ever happen, please refer to the evidence of the events for further comment.

[bizzard]

1 minute ago, Tracy D'arth said:

I cannot understand how; when a calorifier fills from the bottom and empties from the top; this could ever happen, please refer to the evidence of the events for further comment.

The water didn't go in at the bottom. Because no element is used on those boats they'd bunged the caly in any old how. And without demolishing the bed above it was difficult to r- arrange it and re-pipe it up properly.

[Tracy D'arth]

21 minutes ago, bizzard said:

The water didn't go in at the bottom. Because no element is used on those boats they'd bunged the caly in any old how. And without demolishing the bed above it was difficult to r- arrange it and re-pipe it up properly.

What!!!!   If the hot water came out of the bottom, how did they ever get any hot water?

[bizzard]

2 minutes ago, Tracy D'arth said:

What!!!!   If the hot water came out of the bottom, how did they ever get any hot water?

They had horazontal cali's. They had electric water heaters fitted for hot water on the wall instead.

[Tracy D'arth]

6 minutes ago, bizzard said:

They had horazontal cali's. They had electric water heaters fitted for hot water on the wall instead.

Sorry, too confused to work that out, I'll take it as read.

[Simon P]

5 hours ago, blackrose said:

I removed the boss from mine without a problem (no heat required) and fitted an immersion, but I've heard some can be hard to remove and it's not that difficult to rupture the tank if you're not careful. 

 

I had to find a lump in the insulation on my calorifier and carve the foam off to expose the boss, whereas yours looks like a better quality foam application. Hopefully that might suggest a better quality tank too, although why the builder would install it with the immersion boss at the top of the tank seems odd to me. Where's the PRV - at the bottom? 🤔

Yes the PRV is at the bottom🤷🏻‍♂️

[Ronaldo47]

A penetrating oil (such as  Plus-Gas if you can find it, or petrol lighter fluid if you can't) can help to release siezed screw threads.  If it doesn't work immediately, see-sawing the wrench to and fro can have the effect of  pumping the solvent into the inner turns. 

[WulfNut]

Use a blow torch to break the seal if that doesn't work then try to tap it gently with a hammer, if that fails boil a kettle and use the marinas showers.