unvented cylinder but low pressure at outlets in loft?

[ecswtrav]

Hi all,

Hoping someone can help. I've not yet had a plumber out to check, thought I would get some opinions first if possible. What I perceive to be a problem may not be in reality. I have an unvented mains pressure cylinder in the basement set to 2 bar on the PRV from the mains which is correct from reading the manual. 22mm feed in and out of the boiler running off to the to the various rooms. The cold off the mains starts at 22mm but turns into 15mm in the basement and runs to the rest of the house.
The boiler serves a loft bathroom which is 3 floors up. 22mm feed all the way for hot and 15mm for cold. From where the boiler is its approximately 7 meters up to the shower. I've bought a new shower in advance - an aqualisa digital high pressure (bit stupid of me) and at the outlets for the hot its reading 0.8 bar and the cold 1.8 bar. So based on the shower specs anything below 1 bar is a no go.

Due to the height of the shower is this pressure loss entirely normal over that distance on a mains system? or is there potentially an issue somewhere. I'd just like to know whether I should sell the shower and purchase one that runs below 1 bar.

Thanks a lot

 

[ShaunCorbs]

have you confirmed your hot water is at / coming out the tap at 2 bar?

 

[ecswtrav]

Hi, currently in the loft room its the two copper pipes ready for the shower - I've put a pressure gauge on both the hot and cold. I do know on the outside tap at ground level (floor above boiler) the pressure is higher as I checked a while back.

 

[ShaunCorbs]

rough guess height wise from the top of the cylinder to your new bathroom ?

 

[ecswtrav]

probably just over 6 meters - I said 7 above, ignore that. My thoughts were pressure loss because its so high maybe?

 

[ShaunCorbs]

probably just over 6 meters - I said 7 above, ignore that. My thoughts were pressure loss because its so high maybe?

could be

any chance you could post a pic up of your unvented cylinder strange its set at 2 bar

 

[ecswtrav]

its an ideal istor...bit of an old boiler/cylinder unit all in one with a bad reputation from what I've read but I've had very few problems over 5 years...it is serviced each year though and on a service plan. The boiler has a pressure reducing valve preset to 2 bar...even though I can adjust this...which I dont feel comfortable doing really.

 

[fezster]

You lose a bar of pressure for every 10m in height. So 0.8 bar on the hot probably sounds about right. I'm guessing your cold must be direct from the mains, and not through your pressure reducing valve, hence is a higher pressure?

 

[ShaunCorbs]

TBH I would recommend replacing the all in one unit for a boiler and unvented cylinder

Then your hot pressure should be around the same as the cold

 

[ecswtrav]

Thanks for the replies, much that I'd like an upgraded system this one seems to be running ok at the moment. It does have the cold coming straight off the mains from what I can see...should this have a prv too to level the pressure up with the hot?
I've been reading many unvented systems are set at 3bar on the prv before the system...I'm assuming my 2 bar setting probably isn't helping matters and can't be adjusted without the tundish leaking?

 

[ShaunCorbs]

TBH at this point you may have to opt for an electric shower

And correct the maximum your unit is rated at working is 2 bar so leave well alone

 

[ecswtrav]

I found a few Mira showers that operate under 1 bar so I'll check these out perhaps rather than go the electric route...I hate those things...or at least the ones I've experienced have been a dribble.
Thanks for the help