Accumulator replacement

[wordsalad]

Hi all,

 

Our accumulator membrane seems to have broken down, based on its leaking water after the pump runs.

 

I'm planning to replace it, just wanted to sanity check a couple of things before I do... apologies if any of the questions are a bit dim; I haven't done any maintenance on the water system til now.

 

 

Potable water. I've read elsewhere on this forum that accumulators are usually colour coded, where red is for heating and white is for potable water. Does that mean e.g. this model is for heating, despite being in the freshwater category? https://www.marinesuperstore.com/freshwater-system/water-tanks/jabsco-2l-accumulator-tank
It seems perfect otherwise, and I keep coming across ones that look just like it. Some of them are explicitly labelled as suitable for potable, but I'm not sure how much I trust that the descriptions are true.

 

Plumbing fittings. I've attached a photo of our old accumulator, which is plumbed in via hoses connecting to a t-junction. As far as I can tell, that t-junction can't be unscrewed from the current accumulator - despite other accumulators looking like they just have a threaded output. Do I just need to be more forceful? Some special spanner for the plastic bolt?

 

If I can't detach that t-junction, do I just need to get a new t-junction for the new accumulator, unfasten the current hoses' jubilee clips, then refasten them on to the new t-junction?

 

The narrowest part of that t-junction seems to be about 12mm. Does that mean a replacement should be 1/4in? (No idea about standard sizes.)

 

Thanks all, I'm hugely looking forward to fixing this and getting the bilge dry again...

[Tony Brooks]

I would suggest that accumulator is upside down. I am not even convinced it is a diaphragm type.

 

Any accumulator/expansion vessel for potable water will suit as long as it is no smaller, volume wise, that the old one. I would start by looking at the likes of Toolstaion etc. The colour is unimportant as long as it is suitable for potable water. Even better if it says the interior is epoxy coated or some such.

 

 

[nicknorman]

Colour of accumulator is not a reliable guide, look for "suitable for potable water" etc.

As to the plumbing fittings, most people use 15mm push-fit these days but I suppose if the rest of your system is that hose stuff, that might be difficult. Anyway, normally the connection on an accumulator is 1/2" BSP (including the one you linked to) which is the same as a tap, so tap connectors are the thing! And that white plastic T is no use, even if you could get it off in one piece.

You can get a pushfit coupling with 1/2" BSP tap connector on one end and 15mm pushfit on the other, but you'd need a short length of 15mm (plastic) pipe to which you could then attach a push-fit spigot to connect back to the hoses you are currently using, plus a T piece with hose connections all round. Nasty, especially as the hoses will be aged and hard, but the alternative is to replace the lot with modern stuff.

Plumbing is dead easy ... WHEN all the stuff is modern and compatible. When you are trying to mix ancient hoses with modern tap fittings, it's going to be a faff unless you know what to use.

Edited November 1, 2021 by nicknorman

[Jen-in-Wellies]

28 minutes ago, wordsalad said:

I've read elsewhere on this forum that accumulators are usually colour coded, where red is for heating and white is for potable water.

This is not a fast rule. I've got red accumulators and expansion tanks. Both meant for potable water. Go by the description in the sales blurb. Not the colour.

29 minutes ago, wordsalad said:

As far as I can tell, that t-junction can't be unscrewed from the current accumulator - despite other accumulators looking like they just have a threaded output. Do I just need to be more forceful? Some special spanner for the plastic bolt?

It has hexagonal faces on it, so that is likely. Just a close fitting spanner. If you round it off, or break the plastic bit, then you used too much force! I agree with @Tony Brooks. The accumulator is upside down. Usually the pipe entry is at the bottom.

 

Accumulators I've seen have 1/2", or perhaps 3/4" BSP fittings, not 1/4", though a threaded bit around 12mm across suggests 1/4 BSP as you think, so you'll probably need a new T anyway. I've used rigid plastic plumbing and fittings for these things. To mount one on a floor I've used one of these sort of wall plate fittings. Screwed down, it is strong enough to support the accumulator. Others have a mounting bracket to attach the tank to a wall. You can then go to hose fittings to a T, or do the T in regular plumbing with hose tail fir tree fittings on.

Jen

[nicknorman]

One reason for having the accumulator with the water connection at the bottom is so that you can easily get at the Schraeder (air) valve on the other end to check and adjust the pressure.

Cant be quite sure from blurry picture but it looks like the existing accumulator has a female thread for water connection, whereas new ones will have male threads.

Edited November 1, 2021 by nicknorman

[Tony Brooks]

The other reason for having an accumulator the other way up is if it happens to be a non-diaphragm type you need the air bubble trapped at the top. The way this one is would allow the air bubble to escape into the system, then it would not work.

[wordsalad]

Thanks all for your help with this.

 

The white t-piece was, as far as I can tell, built in to the old accumulator. Not sure what that was about; I ended up binning it.

 

I got an adaptor for threaded->hose on the new t-piece, and fingers crossed everything seems dry and functional in the new setup.