Pressure Reducing Valve limiting mains water pressure why?

[Chalked]

I suspect this is diy! But.

A little advice though!

Your cylinder will be rated to 2 bar, because that's the pressure it is rated at. Ie the maximum pressure it will safely take without exploding! I suspect this an non standard prv.
No more advise. Get a G3 engineer in . It wil save you time, money and heartache .

 

[Sparkgap]

So, the Istor PRV is being used for the whole house? Why? Unvented cylinder T&PRVs are normally set at about 3 Bar so the PRV feeding the cylinder would be set to about 2 Bar. These PRVs are designed for certain flow rates and if you have the whole house off them they could be overloaded and not give you the flow rate, especially for baths. Usual procedure is having the PRV feeding the cylinder and only those fittings which need a balanced pressure supply such as shower mixers. The rest of the house can come straight off the mains unless you've got stupid high pressure.
It's not unknown for PRVs to stick, so get your servicing bod to check it out under different flow rates.

 

[ecswtrav]

Sparkgap, yes the istor is being used for the entire house. On page 19 of the install manual it shows the PRV positioned straight after the mains inlet. So basically, the mains is instantly reduced to 2 bar. I've bought a flow measuring cup as the boiler does state to deliver DHW at up to 35LPM. I'm lucky if I'm getting 8 out of most of my taps and the 2 showers. If I adjust the PRV to say 3 bar the flow is really improved but the tundish on the boiler starts passing water. All pipework from what I can see is 22mm too. Does the boiler pump have anything to do with this? perhaps its on its way out? I will be calling out a G3 engineer but I'd just like to have an idea first before what is going on and why on earth would you limit an incoming mains water supply instantly - it defeats the purpose of getting a new mains connection doesnt if you exclude the health benefits? Thanks again

 

[Sparkgap]

Sparkgap, yes the istor is being used for the entire house. On page 19 of the install manual it shows the PRV positioned straight after the mains inlet. So basically, the mains is instantly reduced to 2 bar. I've bought a flow measuring cup as the boiler does state to deliver DHW at up to 35LPM. I'm lucky if I'm getting 8 out of most of my taps and the 2 showers. If I adjust the PRV to say 3 bar the flow is really improved but the tundish on the boiler starts passing water. All pipework from what I can see is 22mm too. Does the boiler pump have anything to do with this? perhaps its on its way out? I will be calling out a G3 engineer but I'd just like to have an idea first before what is going on and why on earth would you limit an incoming mains water supply instantly - it defeats the purpose of getting a new mains connection doesnt if you exclude the health benefits? Thanks again

The blurb for the Istor just shows the PRV on the cold supply to the Istor, not doing the whole house. As I said earlier, all it should be doing is the Istor and any fittings such as showers which require a balanced hot and cold pressure supply leaving the rest of the house on direct mains. If the flow is restricted has the filter in the PRV been checked? As far as I can see there aren't any other filters to be serviced and the only other thing is the hot water mixing valve. If the cold or hot supply to that is restricted for some reason it would cause reduced flow.
Best get your servicing bod to check it out.

 

[ecswtrav]

sparkgap that's really helpful thank you. The annual service is done by a big insurance company and the last bloke didn't have a clue what the PRV was! I even had to explain it! From the new mains - literally where it joins the house - is this PRV. From what you're saying can I assume this is in the wrong place as it seems from this setup the entire house must be limited by this. I assumed from the diagram inside the installation booklet it was in the right place. From what you're saying the PRV should be situated further upstream before the boiler cold inlet and a seperate mains supply leading elsewhere? Is my setup 100% incorrect or would there be an obvious bit of pipe routing that would confirm all is ok? I've ordered a JET PRV with a clear indicator of pressure and I'm going to have a go of fitting it myself when it arrives to see if maybe the old one is clogged up and not working how it should be. I'll let you know how I get on. thanks

 

[ecswtrav]

Looking at this diagram doesn't this indicate that the PRV is right next to the mains so the entire house is controlled by this limiter? Seems strange to be if so? Or am I just not reading this correctly?

 

[Plumbstar Tom]

its drawn like that so that feeds to all mixing outlets are balanced, you don't want different pressures going to showers etc as the higher pressure feed (usually cold) will just over power the other

 

[ecswtrav]

Thanks Tom, is my setup correct then? Mains inlet, PRV then im assuming one pipe going off to the boiler and another for the mixer shower and taps?

For ages I've experienced an initial burst of power with the showers and taps which after a few seconds dies down to the current flow rate. Taps splutter a lot but im led to believe you cant have an airlock in this system so again im holding the PRV culprit.

Does my setup seem ok because I still believe my entire house is limited by the PRV at the mains. Thanks

 

[ShaunCorbs]

Thanks Tom, is my setup correct then? Mains inlet, PRV then im assuming one pipe going off to the boiler and another for the mixer shower and taps?

For ages I've experienced an initial burst of power with the showers and taps which after a few seconds dies down to the current flow rate. Taps splutter a lot but im led to believe you cant have an airlock in this system so again im holding the PRV culprit.

Does my setup seem ok because I still believe my entire house is limited by the PRV at the mains. Thanks

i would say yes unless you want to run a new balance cold to all your showers and hot taps (if mixed)

 

[ecswtrav]

thanks Shaun, I've looked over it all and it seems to be installed just as the diagram states. I'll know more when I replace the PRV - maybe it is the culprit but having said that I'm not hopeful in going from 8LPM to the 35LPM in should be giving out - particularly if the PRV is set at 2 bar.