Mains water pressure reducing vale for boiler?

[ecswtrav]

Hi All,

Hoping you can advise. I'm no expert on the boiler front but i'm trying to figure something out. I have an Ideal istor boiler with a vented cylinder and boiler all in the one unit. The boiler has a shocking reputation but touch wood it's been great for 2 years since moving into the house apart from a recent pump change.
Anyway, before the new pump and since then I'm not too sure if the flow rate out of the taps is what it should be. We have recently had the old lead mains replaced and I was hoping for better water flow out of the taps and in showers but there is no difference at all. The flow is ok but it certainly isn't powerful. The piping throughout seems to be 22mm.
At the new mains there is a PRV with a gauge. This sits at 2 bar and on reading the boiler manual it has to limit the water to 2 bar for the boiler to work apparently? I tweaked the valve to release more water pressure but on doing so noticed the boiler started leaking water from the tundish assuming a valve was giving way due to the pressure increase? The taps etc did have a lot more flow though! On reducing the pressure on the PRV there is no leaking from the tundish but the flow rate is back to being 'so so'.
So, is there any way to increase the flow of water from the boiler or is it performing how it should be? The boiler is situated in the basement and there are 2 floors above that and a small basement conversion with a shower in. I can understand the top floor struggling - it's a really low flow rate up there and the mixer shower operates like an old electric one. But even the kitchen sink just offers a nice steady medium flow?
Can anyone offer any suggestions for increasing the flow rate or is it simply the boiler limitations and I'll have to live with it? Thanks a lot

 

[kris]

By you increasing the pressure on the boiler gauge has no effect what so ever on your hot water pressure. The pressure your increasing is the pressure inside the radiators. As long as your mains is fully open. There is a valve that be best if you get a g3 guy in to set pressure but chances are should be already set.

 

[kris]

Sorry ignore the bit about g3 as just noticed it's vented cylinder . But pressure points is right so.

 

[Ermintrude]

Whole house booster pump. Or unvented

 

[ecswtrav]

Kris, I'm not increasing pressure on the boiler gauge. I'm doing nothing directly to the boiler. Its the mains water where it enters the house - there is a Pressure Reducing Valve that reduces the pressure of the water entering the property - this is not the pressure dial on the boiler. This is because the boiler itself cannot receive the full pressure coming through from the new water mains - certain components such as the pressure relief valve within the boiler give way at 3bar and cause dripping in the tundish. The boiler installation manual explains that the mains pressure supply to the boiler shouldnt be more than 2bar.
This 2 bar limiter means the water flow coming out of the taps/shower is average at best. Turn up the pressure at the mains and the flow is great a 3 bar but the boiler isn't set properly and then the valves leak.
Just seems a strange requirement of the boiler but I wouldn't know whether this is normal or not.
I may look into this booster pump Ermintrude - I assume this is fitted upstream of the boiler?

 

[Dotty]

Nothing's adding up. What's the make and model of this boiler?

 

[jase158]

Nothing's adding up. What's the make and model of this boiler?

As above, you wouldn't have mains if you have vented cylinder, this would be pressure to tank in loft then the loft down to the taps would be lower pressure. but you say that the tundish leaked??? pics please???

 

[jase158]

ah I see!!
one of these!!
Ideal Istor HE combined system boiler & cylinder

As said before you need a G3 registered engineer!!!

 

[mache]

Get someone in to have a look. Your prv might be doing a great job on pressure control but sounds like its volumetric flow rate in operation is poor. Have you measured your flow rate from taps ??

 

[Ermintrude]

If it's an Istor just burn house down. Wash yourself with mind bleach and hope for a quick death.

 

[dmheat]

Ok. The istor has a pressure reducing valve preset to 2bar and a temp and pressure relief valve set at 4bar. By increasing the inlet pressure you've either hit the 4bar on the tprv straight away or it's hit 4 bar once it's up to temp through expansion.

What you have done is a very bad idea and I strongly suggest immediately turning it down back to 2bar.

If you have a 22mm cold main up to the boiler and 2bar reading on the gauge your flow rate should be decent. First port of call....get it serviced. You not only have a boiler, you have an unvented hot water cylinder there, BOTH of which require annual servicing and checking of the safety devices.

I have a decent idea of what's probably causing your poor flow rate, so will the GSR you get to do your servicing