"Tim+" wrote in message
...
wrote:
On Thursday, April 25, 2013 10:19:43 AM UTC+1, Tim+ wrote:
I'd like to experiment with using a 2L coke bottle as a pressure
vessel but I haven't worked out how best to make a leakproof plumbed
connection to the bottle.


http://www.mindsetsonline.co.uk/prod...roducts_id=354

Nice, but I think the connections would be just too small. I want it to
act as a pressure reservoir to prevent rapid pump cycling in a motorhome
pumped water system. The exisiting system uses a pressure switch which
was okay with the old pump but a new uprated pump is causing problems and
the recommended solution it to fit a pressure accumulator

Of course I could just spend lots of dosh and buy the recommended one but
it's more fun to try and do it on the cheap. ;-)

http://www.ebay.co.uk/itm/SHURFLO-Ac...item27d2223cd7

Firstly, a 2 litre pop bottle is pretty flimsy, whilst it will handle the
couple of bar pressure in a motorhomes water system, can it handle the
vibrations and movement from driving down the road... basically if it fails,
you will pump the contents of the water tank into the living area,

secondly, the 'proper' accumulator has a diaphragm inside it, water on one
side, air on the other, it's the compressible air the other side of the
diaphragm that acts as the buffer,
Last one i bought for the cold side of the water system in my motorhome was
fiamma branded, and cost me about £14, looked similar to the one you showed,
but blue,

Problem with that one you linked to, they have mentioned 'boat' in the
listing, and as soon as you try and sell something to the boaty types you
double or tripple the price, and get away with it, motorhome part prices are
expensive enough, but boat parts... whilst often the exact same thing, are
just a **** take.

When i fitted the eberspacher based central heating and hot water tank, i
fitted a 7 litre hot water accumulator to the hot pipework (the 20 litre
calorifier needed it to stop the hot water being pushed back down the cold
pipework when the tank was heated)
The 7 litre expansion vessle was only 20 quid,

Not sure where you live, but have you heard of places like magnums,
O'leary's etc,
they are based in grimsby and hull, but there are a couple of similar places
down south... cant remember the names now... franks caravans is one i'm
sure,
they sell motorhome parts at more realistic prices, and sell the stuff for
home builders of motorhomes, and they also buy up last seasons stock from
manufacturers when they change things in their builds, so you can get things
a lot cheaper from them.