Weird (to me) domestic water system setup

[fergycool]

I'm getting to know my boat better and it's the turn of the plumbing of the domestic water. I've traced all the pipework and found that it does not seem to fit any standard setups I've read about. Basically there is no pressure release valve at all (worrying!) and the accumulator seems to be in a wrong place.

Here's how it looks now:



The lack of a PRV does worry me, although the rating of the calorifier is 160PSI. Also most of the pipework (other than the hot water side) is poly hose. I guess that would go before the cylinder would.

I aim to modify this somewhat by inserting a PRV at the place marked by the X and also teeing the Accumulator to there instead of its current location. I'll plumb the output of the PRV into the breather hose rather than into the bilges.

Does that sound about right?

Thanks!

 

[neale]

Are you sure there is not a prv on the calorifier?

 

[neale]

The accumulator in that position would deal with the expansion caused by the heated water, it would also even out the flow on the hot water side but I imagine the cold taps pulse quite badly unless the pump is one of the variable flow types.

 

[fergycool]

There is no PRV on it. It's a very old calorifier. There's just a single coil from the engine and two hose connections for input and output. In fact I'm suspicious that it actually is a calorifier. It looks more to be like it's just a pressure vessel of some sort that somebody has adapted in the past. It's in fair condition though.

 

[fergycool]

The accumulator in that position would deal with the expansion caused by the heated water, it would also even out the flow on the hot water side but I imagine the cold taps pulse quite badly unless the pump is one of the variable flow types.

The cold water flow is OK although the pump does come on every 20 secs or so. Would moving it to the new position help for both?

 

[neale]

Maybe the accumulator was placed where it is to specifically deal with the pressure increase on the hot water side.

 

[neale]

An accumulator in position x will even the flow on both hot and cold. There should be a nrv on the inlet pipe of the calorifier too.

 

[vyv_cox]

It is perhaps more conventional to have the accumulator close to the pump to smooth the flow. Accumulators are sometimes fitted as yours because there is a non-return valve on the calorifier inlet to prevent hot water from expanding back to the cold taps. If there is no NRV the accumulator in the more conventional position can cope with expansion in the calorifier.

Some time ago I calculated the effects of heating a 25 litre calorifier full of water. When expansion of the (copper) vessel is taken into account the actual volume change is not very large.

 

[nigelmercier]

Apart from the lack of PRV, and the placement of the accumulator, I think this is standard, isn't it?

I currently don't have an accumulator, I thought I'd try my new pump without.

 

[NormanS]

I presume that the cold supply to the calorifier actually goes in at the bottom, rather than the top.

 

[fergycool]

That's just poor drawing on my part. It goes in at the top along with the other connections. The calorifier is on its side. So the cold water inlet was at the bottom but there's not a great deal of difference between the inlet and outlet!

 

[fergycool]

Errrr. I took the calorifier off yesterday and flushed out both the tank and the coil. However, I also noticed the legend "property of Britvic Corona" on the side. Looks like this is not a calorifier but one that somebody made out of a pressurized gas container used for making fizzy drinks no wonder it has such a high pressure rating! I think I need to replace this! Damn I've just had to replace the gearbox. This boating business is wearing my wallet thin.

 

[NormanS]

Errrr. I took the calorifier off yesterday and flushed out both the tank and the coil. However, I also noticed the legend "property of Britvic Corona" on the side. Looks like this is not a calorifier but one that somebody made out of a pressurized gas container used for making fizzy drinks no wonder it has such a high pressure rating! I think I need to replace this! Damn I've just had to replace the gearbox. This boating business is wearing my wallet thin.

Definitely, we cant have you sailing about with the wrong labels you know. Even if it does work.

 

[fergycool]

Definitely, we cant have you sailing about with the wrong labels you know. Even if it does work.

I like labels. I generally get stuck with revolving doors that have "exit" on both sides as I cannot leave the revolving door.

I'm not sure what to do. It's full of "debris" which I assume to be limescale (currently got some descaler doing its job). There's also no PRV (my original post in this thread) which I will have to add. Furthermore the only insulation is some fibreglass blankets (covered in plastic). That all takes up a lot of space.

 

[NormanS]

I like labels. I generally get stuck with revolving doors that have "exit" on both sides as I cannot leave the revolving door.

I'm not sure what to do. It's full of "debris" which I assume to be limescale (currently got some descaler doing its job). There's also no PRV (my original post in this thread) which I will have to add. Furthermore the only insulation is some fibreglass blankets (covered in plastic). That all takes up a lot of space.

If the PRV turns out to be the only problem, it could easily be "Teed" into the outlet connection.

 

[vyv_cox]

I suspect that your hoses would burst before your calorifier does in view of its rating. If you didn't have a calorifier you would not have a prv at all. Your pump can only deliver a couple of bar at best, heating the water may increase it a little but the extra will mostly be absorbed by the accumulator. So why worry?

 

[fergycool]

I suspect that your hoses would burst before your calorifier does in view of its rating. If you didn't have a calorifier you would not have a prv at all. Your pump can only deliver a couple of bar at best, heating the water may increase it a little but the extra will mostly be absorbed by the accumulator. So why worry?

You are right. I think I'll put it all back together and actually use the boat instead of plumbing in it! Thanks to all who helped me on this thread.