jambo

[jambo]

hey guys got a unvented system will be starting soon customer wants mixer shower but and this is a big but mains pressure is only 1-1.5 bar need serious advice on this one please cheers guys

 

[wiltsplumb]

wouldnt consider puttting in unvented cylinder on 1 to 1.5 bar performance would not justify cost of unvented cylinder.

 

[wnjswozo]

agree with wiltsplumb,but shower not a problem just put a shower pump on for mixer,you need a new cold main putting in.

 

[jambo]

oh dear not good news is ther no way round this problem at all house is that big it has two vented cylinders runnin off a worcester reg boiler HELP job comin next week what would be the outcome if fitted on this low pressure mains

 

[Billy Bob Bob]

you cant go unvented what about conventinal tank/cylinder

 

[jambo]

any way of upping the mains

 

[Billy Bob Bob]

oh dear not good news is ther no way round this problem at all house is that big it has two vented cylinders runnin off a worcester reg boiler HELP job comin next week what would be the outcome if fitted on this low pressure mains

it would not work

 

[wiltsplumb]

if you put in an unvented cylinder with that low pressure performance will suffer massively only real option is to replace water main using 25mm mdpe you also need to check flow rate as that is just as important !!!

 

[Billy Bob Bob]

oh dear not good news is ther no way round this problem at all house is that big it has two vented cylinders runnin off a worcester reg boiler HELP job comin next week what would be the outcome if fitted on this low pressure mains

sorry dident se this first what about renewing like for like,converting to fully pumped and raising the head of the tanks if possible this will give a pretty good shower

 

[jambo]

tanks are as high as they can go bud so in a nutshell unvented no go

 

[Billy Bob Bob]

fraid so you could have expensive issues renewing the cold main,whats the dhw flow like at present?

 

[jambo]

what is the min you can run an unvented bar wise

not sure yet is ther a calculation you can work out with the mp or has to be done with a flow cup

hot is same as cold which is gravity fed

 

[wiltsplumb]

oops didnt read first post properly either!!

 

[Billy Bob Bob]

what is the min you can run an unvented bar wise

not sure yet is ther a calculation you can work out with the mp or has to be done with a flow cup

hot is same as cold which is gravity fed

thats not good means cold is poor

 

[jambo]

so in a nut shell am goosed

 

[wiltsplumb]

ariston reccomend minimum of 1.5 bar and 20 litres per min but if large property with numerous outlets i would still not do it

 

[Billy Bob Bob]

well you could go back conventional and fit a shower pump

 

[jambo]

cheers guys looks like am F****D

 

[Blackcatgas]

100 gallon tank in the loft, connected to salamander super booster pump, cant remember exact model, csp 120?, this is then connected to the cylinder, Ive just fitted a pair of these, one for hot one for cold, with 2 showers, 1 bath and 2 baqsins running full pelt the pressure and flow rate was still awesome.
yes esp 120 super booster single pump, 3.6 bar just the job! £250 ish though.

 

[jambo]

any chance you could tell me exactly wher you locate the pump in the loft please

 

[Mackattak]

Use an accumulator cylinder, this will increase flow rate to the unvented cylinder.

GAH - Dualstream Mains Pressure Hot Water Cylinders - Key Benefits of Dualstream

Try this website

ColdStream Hot and Cold Water Control

 

[jambo]

so will i not need the pump from storage tank in loft or does accumilator tank take care of thr pressure

 

[Mackattak]

Do away with the pump and the tank. Mains water fills up the tank expanding the baffle inside the cylinder. Once a draw off is opened it releases its charge giving high flow rate. Put this before the unvented cylinder so it just works the hot water.

If there water pressure is really bad you can get a pump on the inlet side of the accumulator.

 

[jambo]

cheers bud

for speed wd it not be easier to put pump on in loft to feed the unvented in which case where is the pump situated

 

[Blackcatgas]

cheers bud

for speed wd it not be easier to put pump on in loft to feed the unvented in which case where is the pump situated

Pump needs to be a certain distance below the tank, ideal next to the cylinder.