How to fit an expansion vessel?

[Karen Lea Rainey]

My calorifier does not currently have either an accumulator tank or expansion tank fitted.

Everytime I use either the engine or eberspacher for heating / hot water, my prv opens and sends drips of water into my bilge.

I pride myself on having nice clean and dry bilge, given that there will be little work for the bilge pump to do except from the few drops of water from the stern gland.

I am planning to fit an expansion tank in the hot water outlet from the calorifier,  the plan is  to put a 't' piece joint in the pipe and reduce the work that the prv is  likely to do.

I have a 55 litre surecal calorifier, with hydronic w5 eberspacher and engine coil dual ( twin coil internal pipes).

The calorifier is under the bed, horizontal and all of the water feed pipes are positioned at about the 9 o clock position as you look at it end on.

The pipes all then go 90 degrees of the calorifier to the floor and go off to the taps ,radiators, prv leak off pipe etc. And travel along the floor/ skirting board.

I realise that I need to empty the calorifier somewhat before creating a 't ' piece in the hot pipe, but how do I make sure that the contents of the calorifier are "emptyish"  and I dont get a flood of water everywhere when I break open the pipe.

Should I turn of the feed in from the water tank ?

and just run the hot tap until its empty?

will it ruin the water pump to just pump air?

Turn the prv valve to purge the water out?

Or is there any other way to reduce the amount of water lost when fitting the 't' piece

[blackrose]

My calorifier is vertical so it might be a bit different, but when I tried to empty it to install a mains immersion heater I couldn't actually get any water out because the vacuum in the tank held it in. I had to twist the PRV on the top of the calorifier to release the vacuum and empty water into a washing up bowl. When the bowl was full I simply let go of the PRV to stop the flow.

 

You should of course turn off the water pump and any other isolators you have and open a couple of taps to release the pressure in the system before you start. Have some towels handy too.

 

Also make sure your expansion vessel is stainless or epoxied otherwise it will quickly corrode from the inside. Ask me how I found out about that...!

Edited February 8, 2022 by blackrose

[blackrose]

1 hour ago, Karen Lea Rainey said:

 

I realise that I need to empty the calorifier somewhat before creating a 't ' piece in the hot pipe

 

You can put the T into the hot outlet pipe from the calorifier, but I think most people T into the cold feed pipe to the calorifier, downstream of the non-return valve (i.e. between the NRV and calorifier). If there is no NRV on that cold feed pipe then I'd look for other reasons as to why your PRV is weeping because without a NRV the expansion should be accommodated by the cold feed pipe.

Edited February 8, 2022 by blackrose

[Karen Lea Rainey]

Thank you, 

There is an NRV (none return valve) on the cold feed in , hence the prv working correctly when the water heats up.

So, will the water be generally held  in the calorifier due to a vacuum being created, ie just a little spillage?

[Bee]

I've probably read this wrong but shouldn't the expansion thingy go somewhere on the hot water inlet side? somewhere in the engine, eberspacher cylinder circuit?

[Tony Brooks]

1 hour ago, Karen Lea Rainey said:

The calorifier is under the bed, horizontal and all of the water feed pipes are positioned at about the 9 o clock position as you look at it end on.

 

That sounds wrong to me. The coil pipes I would agree with being at 9 & 3 but I would except the inlet to be more or less at 6 and the hot outlet at 12, Otherwise you would never get at the hot water in the cylinder that is above the outlet unless the manufacturer fitted "dip tubes" inside the calorifier and I have never heard of that..

 

If it turns out the hot outlet is at the top then pump off, taps open, and get a bucket or tray and rags under the place you are going to break into the pipe to catch any  water that comes out. It should only be what is in the pipes to tap height so probably it won't be much.

 

Personally I would definitely fit it into the hot out pipe at any where between the calorifier and first tap that is convenient. That is where most people expect to find it. If you put it on the inlet between the/a NRV and calorifier it is all too easy to  mistake it for an accumulator.

4 minutes ago, Bee said:

I've probably read this wrong but shouldn't the expansion thingy go somewhere on the hot water inlet side? somewhere in the engine, eberspacher cylinder circuit?

 

In my view no because to identify it as an expansion vessel you would need to see where t is  relative to the NRV where as if it is in the hot outlet side it is obliviously an expansion vessel. The accumulator goes into the cold inlet side between pump and NRV although mounting it near the calorifier is probably not usual.

[agg221]

15 minutes ago, Tony Brooks said:

 

That sounds wrong to me. The coil pipes I would agree with being at 9 & 3 but I would except the inlet to be more or less at 6 and the hot outlet at 12, Otherwise you would never get at the hot water in the cylinder that is above the outlet unless the manufacturer fitted "dip tubes" inside the calorifier and I have never heard of that..

 

If it turns out the hot outlet is at the top then pump off, taps open, and get a bucket or tray and rags under the place you are going to break into the pipe to catch any  water that comes out. It should only be what is in the pipes to tap height so probably it won't be much.

 

Personally I would definitely fit it into the hot out pipe at any where between the calorifier and first tap that is convenient. That is where most people expect to find it. If you put it on the inlet between the/a NRV and calorifier it is all too easy to  mistake it for an accumulator.

 

In my view no because to identify it as an expansion vessel you would need to see where t is  relative to the NRV where as if it is in the hot outlet side it is obliviously an expansion vessel. The accumulator goes into the cold inlet side between pump and NRV although mounting it near the calorifier is probably not usual.

Two observations here, the first somewhat speculative.

 

The OP says that all the feeds are at the 9 o'clock position. I wonder whether that is all the outlet feeds, with the inlet at the 3 o'clock position? If so, I suspect that the calorifer was installed rotated by 90degrees. Since it is under the bed, I suspect that would have been for reasons of access and height. As you state Tony, that would mean half the calorifer was not actually delivering hot water. If the OP does not run out of hot water, I would leave it alone. If however they do, I would look to rotate it as close to upright as possible (11 o'clock or 10 o'clock) to improve utilisation. It's a lot more plumbing work and may involve some funny angles. I would go for buying a pipe bender and using compression fittings, rather than a whole load of soldered bends.

 

For functional reasons, I would fit the expansion vessel in the cold water feed, particularly if you are in fact only using half the hot water. On expansion, water is pushed up the pipe into the expansion vessel. If the expansion vessel is on a hot water outlet then the water pushed out is hot. Once it reaches the expansion vessel it cools, meaning that you have to run that much water through to get hot water. If however the vessel is in the cold water feed which is placed near the bottom then the water pushed out is likely to be colder and even if the temperature has homogenised, the water will re-heat when it re-enters the calorifer, resulting in closer to instant hot water from the system. Depending on pattern of use, this could result in a considerable difference in water consumption.

 

Alec

[Karen Lea Rainey]

Hi guys, thanks for your replies so far, perhaps it's not a surecal branded calorifier, 

And it's  some other manufactured brand.

Every pipe either going in or out of the calorifier is at 9 o clock,

There are only 5 points of entry / exit fittings, there is no immersion fitted, the whole tank is covered from top to bottom in foam except for  eberspacher  in and out (2)

Engine coil pipes in and out (2)

PRV Exit pipe hose (1).

All entry exit pipes are about 2 inches apart in a straight row along the length of the horizontal tank.

[agg221]

2 minutes ago, Karen Lea Rainey said:

Hi guys, thanks for your replies so far, perhaps it's not a surecal branded calorifier, 

And it's  some other manufactured brand.

Every pipe either going in or out of the calorifier is at 9 o clock,

There are only 5 points of entry / exit fittings, there is no immersion fitted, the whole tank is covered from top to bottom in foam except for  eberspacher  in and out (2)

Engine coil pipes in and out (2)

PRV Exit pipe hose (1).

 

Presumably there is also a cold water in?

 

Alec

[Karen Lea Rainey]

1 minute ago, agg221 said:

 

Presumably there is also a cold water in?

 

Alec, 

Yes sorry plus the cold feed in and hot water out feeds (+2 more).

 

Just now, Karen Lea Rainey said:

 

But still all in a straight row .

[David Mack]

If the hot water out pipe is at the bottom then it must have an inverted 'dip pipe' inside to draw hot water from the top of the calorifier. And probably some trapped air in the top which you can't bleed out, which will increase the amount of water coming out of the PRV as it expands whenever the calorifier is heated.

[Tracy D'arth]

57 minutes ago, Bee said:

I've probably read this wrong but shouldn't the expansion thingy go somewhere on the hot water inlet side? somewhere in the engine, eberspacher cylinder circuit?

No.

[Jen-in-Wellies]

2 hours ago, Karen Lea Rainey said:

I realise that I need to empty the calorifier somewhat before creating a 't ' piece in the hot pipe, but how do I make sure that the contents of the calorifier are "emptyish"  and I dont get a flood of water everywhere when I break open the pipe.

In answer to one of your original questions. It should be possible to do this without having to empty the cauliflower at all. There will be a few drips coming out of the disconnected inlet pipe while you put in the T to the expansion vessel, but no flood. I've done exactly this on a vertical calorifier, but a horizontal one should be no different. As long as all the hot taps are closed and the PRV is closed, then little water will come out as there is no way for air to get in to replace it. Similar to filling a glass in a bowl of water, then turning it upside down underwater and slowly drawing it up out of the bowl. The water stays in the glass till the rim breaches the surface. You'll need some towels to mop up the drips, but that should be about it. I'd get everything else set up first, the expansion vessel and other pipework and do the T piece as the final stage, leaving it open for as short a time as I could.

If you do want to empty the cauliflower for your own peace of mind, then you actually need to open a hot tap, or twist the PRV knob till it is open to let air in to the top, before any water comes out. You can use the PRV as an on/off valve to let out water in to a bucket, or bowl, then close it while you empty the bowl, ready for the next gallon or two.

Jen

Edited February 8, 2022 by Jen-in-Wellies

[Tracy D'arth]

You could fit the expansion vessel to the cold feed in, after the non return valve, on any hot pipe out or even the pipe to the prv. I does not have to be under the bed.

Is there room in the kitchen sink cupboard? Being up off the floor would mean less spill when you cut the pipe.

Why not fit an in accumulator the the cold supply whilst you are at it? It will give the pump an easier life and be quieter for the small use in the night too.

Edited February 8, 2022 by Tracy D'arth

[ditchcrawler]

1 hour ago, Karen Lea Rainey said:

Thank you, 

There is an NRV (none return valve) on the cold feed in , hence the prv working correctly when the water heats up.

So, will the water be generally held  in the calorifier due to a vacuum being created, ie just a little spillage?

Its not held in by Vacuum, its filled from the bottom and comes out of the top. 

[nb Innisfree]

FWIW on Innisfree I installed the accumulator just after the pump and instead of a non return valve (which would have neccesatated an additional expansion vessel between NRV and PRV to stop hot water expanding back to cold tap feed) I arranged for a dedicated calorifier cold feed  (approx 4 metres in length) so that hot water had somewhere to expand into. I also installed PRV take-off at the calorifier bottom inlet, that allowed compressed air to be introduced via a hot tap, this allowed calorifier to be emptied via PRV when it was manually opened. Worked a treat, very handy. 

Edited February 8, 2022 by nb Innisfree

[nottheone]

Is it possible that this is a vertical calorifier that has been fitted horizontally ? Might explain the odd description of the pipe locations.

Edited February 8, 2022 by billso

[Tony Brooks]

13 minutes ago, billso said:

Is it possible that this is a vertical calorifier that has been fitted horizontally ? Might explain the odd description of the pipe locations.

 

That sounds more that likely except the hot outlet is usually in the top so when horizontal it would be in the end, not the side (assuming side means along the cylinder's length.

[Karen Lea Rainey]

3 hours ago, Tracy D'arth said:

You could fit the expansion vessel to the cold feed in, after the non return valve, on any hot pipe out or even the pipe to the prv. I does not have to be under the bed.

Is there room in the kitchen sink cupboard? Being up off the floor would mean less spill when you cut the pipe.

Why not fit an in accumulator the the cold supply whilst you are at it? It will give the pump an easier life and be quieter for the small use in the night too.

Thanks, just checked the possibilities of where to site it, I can put it under the vanity unit on a shelf in the toilet/ shower/ wash basin sink,

It should fit nicely on the internal shelf and hopefully wont lose to much water plumbing it in.

[Eeyore]

Just curious about the 9 o'clock to 3 o'clock layout.

Can you name them left to right ie starting at the 9 o'clock position?

[Karen Lea Rainey]

2 minutes ago, Eeyore said:

Just curious about the 9 o'clock to 3 o'clock layout.

Can you name them left to right ie starting at the 9 o'clock position?

I will take a picture later, basically every pipe in or out is on the side of the tank, there are no open ends on the calorifier, they are sealed over with foam. They are lined up like buttons on a shirt, if I looked at the tank end on, every pipe is in a parallel line at the 9 o clock position.

[Tracy D'arth]

This is beginning to sound like a vertical calorifier mounted horizontally. If so how it ever works is a wonder? Is there an immersion heater or the boss for one on either end?

[David Mack]

7 minutes ago, Tracy D'arth said:

This is beginning to sound like a vertical calorifier mounted horizontally. If so how it ever works is a wonder? Is there an immersion heater or the boss for one on either end?

This is a typical vertical calorifier - pipe connections all in a row on the side, apart from the hot water outlet.

And this is what a typical horizontal calorifier looks like. Connections all on the end.

[blackrose]

12 hours ago, Bee said:

I've probably read this wrong but shouldn't the expansion thingy go somewhere on the hot water inlet side? somewhere in the engine, eberspacher cylinder circuit?

 

Anywhere downstream of the NRV is effectively part of the hot water pressure vessel (calorifier) including the cold feed pipe to the calorifier.

 

There is no hot water inlet side. Water is fed into the calorifier cold and leaves the calorifier hot (assuming it's heated).

 

I think you've got the wrong end of the stick here. We're talking about fitting a hot water expansion vessel for fresh water, not engine or eberspacher coolant.

[blackrose]

8 hours ago, David Mack said:

This is a typical vertical calorifier - pipe connections all in a row on the side, apart from the hot water outlet.

And this is what a typical horizontal calorifier looks like. Connections all on the end.

 

In that case I must have a horizontal calorifier installed vertically! But mine is basically a cheap marinised household cylinder. Lots are.

Edited February 8, 2022 by blackrose