Accumalator

[jddevel]

Advice on sizing an accumulator please. What information does one need to know? Thanks

[NMEA]

Biggest you can fit and don't buy a red one. Adjust it to just below the pump cut in.

[jddevel]

Any reason why not red? Seems a strange piece of advice or are you diplomatically referring to a "brand"

[nicknorman]

No, red ones tend to be for heating systems i.e. not for potable water supplies. The size isn't that critical but the larger the accumulator, the less often the pump will cycle on and off when the tap is partially open

Edited October 16, 2016 by nicknorman

[matty40s]

About 90% of boat water systems I have seen have red ones.

[Chewbacka]

It seems to be convention, but not a rule, that accumulators are blue and set to a bit below the pump turn off pressure whereas an expansion tank is red, connected to the hot water side of the system (required if there is a non return valve, which is a good idea) and pressurised to just above the pump turn off pressure.

[nicknorman]

About 90% of boat water systems I have seen have red ones.

I expect 90% of boats you see also have crap wiring but that's no reason to encourage it! Anyway blue for potable, red for not potable (and maybe no diaphragm) so if the OP wants to fit an unpotable acc. to a potable water feed, up to him.

[dor]

Mine are silver. Where should I install them? (no rude answers please!)

[Ex Brummie]

Potable expansion vessels are also white. Your silver ones are also potable, but I would imagine are quite small and usually used to eliminate 'water hammer' on combi boilers.

[bottle]

Mine are silver. Where should I install them? (no rude answers please!)

 

Accumulator just after the pump or anywhere that is convenient between the pump and the first outlet (tap).

 

Expansion just after the outlet for the hot water on the calorifier or anywhere convenient between the calorifier outlet and the first outlet (tap).

 

This is the 'norm'

[Chertsey]

I was going to ask what sort of wireless you were wanting to run off it... in your butty...

[PaddingtonBear]

Ho Ho Ho , you beat me to it:)

[dor]

Mine are silver. Where should I install them? (no rude answers please!)

Sorry, wasn't meant to be a serious question! (They are both five litre).

[MtB]

Potable expansion vessels are also white. Your silver ones are also potable, but I would imagine are quite small and usually used to eliminate 'water hammer' on combi boilers.

 

 

Once they get down to the size used to eliminate water hammer, their name changes to 'shock arrester'.

And I almost never see them on combi boilers, but almost always on thermal stores.

[MtB]

Advice on sizing an accumulator please. What information does one need to know? Thanks

 

 

Mine is about five litres and blue but as others have said, size really isn't critical.

 

Bear in mind the size you need might be affected by your choice of calorifier. If you choose a calorifier that relies on the water pump accumulator for expansion accommodation on heating, follow the calorifier instructions. Most calorifiers these days don't though, they require a separate expansion vessel (same thing, performing a different function) of their own.

[PaddingtonBear]

Can I suggest you go nap Dusty Carpet in the 3.30, will take a lot of beating.

[Scholar Gypsy]

 

 

Mine is about five litres and blue but as others have said, size really isn't critical.

 

Bear in mind the size you need might be affected by your choice of calorifier. If you choose a calorifier that relies on the water pump accumulator for expansion accommodation on heating, follow the calorifier instructions. Most calorifiers these days don't though, they require a separate expansion vessel (same thing, performing a different function) of their own.

 

 

And I think this means the OP needs to work out if there is a non-return valve on the cold water inlet to the calorifier. If there is then the accumulator can't fulfil the expansion function described here.

[cuthound]

Accumulator. That was an old term for a battery wasn't it?

[MtB]

Accumulator. That was an old term for a battery wasn't it?

 

Yes. It's also the name of a type of bet on the horses, hence PB's cryptic advice.

 

And yes the presence or otherwise on a NRV in the cold inlet differentiates between the two types of cauliflower.

[nicknorman]

Yes. It's also the name of a type of bet on the horses, hence PB's cryptic advice.

That one had gone "whoosh" right over my head but it all makes sense now. Well I did have a sheltered childhood!

[DHutch]

Yeah, you want something that claims to be suitable for potable water, otherwise, almost anything.

I actually ended up buying our last one via email from a camping and caravan supplier, as where its installed there is not a huge amount of space.

From memory the one fitted is 1L one, which fits with about how much we get out once the pumps turned off, I see little to gain from going larger, certainly not unless you adjust the pressure switch arrangement to cut in-out on a narrower range.


Daniel

[jddevel]

Regarding the reference to NRV`s in my domestic/house environment I tend to fit them in any location I believe drinking

water may be affected and a potential "crossover" between hot and cold water and sanitary equipment.

[NMEA]

I see little to gain from going larger, certainly not unless you adjust the pressure switch arrangement to cut in-out on a narrower range.

 

 

Daniel

The rationale for using a larger one is fewer on / off cycles of the pump, arcing at the contacts is what reduces switch life, the fewer the instances of arcing the longer the contact life, also the pump usually draws more current at start up so one uses less power. Couple that to the advantage of being able to fill a kettle at 5 in the morning or flush a FW head if fitted with reduced noise makes it worthwhile, especially as the cost difference between a 2l & 5l pot is minimal, it can actually be cheaper due to the volume production of the larger ones.

[DHutch]

The rationale for using a larger one is fewer on / off cycles of the pump, arcing at the contacts is what reduces switch life, the fewer the instances of arcing the longer the contact life, also the pump usually draws more current at start up so one uses less power. Couple that to the advantage of being able to fill a kettle at 5 in the morning or flush a FW head if fitted with reduced noise makes it worthwhile, especially as the cost difference between a 2l & 5l pot is minimal, it can actually be cheaper due to the volume production of the larger ones.

 

Yeah, if you have space for a large one is certainly does no harm, but I find typically that even with a 1l (silver in my case) jobby its very raire the pump cuts in/out more than once per tap operation. Given they typically last years even on the hundreds of boats with an accumulator the switch must be reasonably robust.

 

As you say, over the 5l ones are cheaper than the 1l ones and does allow a kettle fill without running the pump, but they also get quite big externally and we dont have the space where the pipe runs are and I can still get a pint or two of water out in the middle of the night.

 

So yeah, either !

 

Daniel

 

 

Daniel