Pressure Reducing Valve - Where one or many

[NewToAllOfThis]

Although not tested yet, I know the incoming pressure in high coming into our new property and neighbours all say pressure is high.

 

Is there a set pressure that should be distributed around the house or does it vary depending on size of property, number of bathrooms, type of heating, etc.

 

We are having a combi boiler installed so no water storage tanks, I assume everything will therefore be at the same pressure throughout unless regulators are added?

 

Should just one PRV be fitted where the mains water enters or should more than one be installed for different applications.

 

We are having an outside tap fitted, would it be better to fit this before the PRV from the mains water so it has a high pressure ?

 

I guess there are good and bad PRV's, can anyone recommend a sensibly priced reliable unit.

 

 

 

 

 

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[JohnMo]

 H, Ii put mine after the stop cock, the outside tap take off and a Y type strainer, but before any inside house offtakes. 

 

I think they normally come pre-set at 2.5 Bar.  I fitted a Honeywell from either Toolstation or Screwfix.

[Nickfromwales]

Honeywell or Reliance are the industry standards.

 

Defo have the outside tap directly off the rising mains, and then the primary PRedV.

If the pressure is that good, I would have a dedicated cold feed going to WC's and appliances only, and have that at 4 bar, and then T off after the stopcock for a secondary PRedV to service the house / bathing at 3 bar. The combi is a "cold mains dependant" device, so anything you can do to preserve the dynamic flow / pressure to it ( so thus to DHW ) is a pursuit well worth the effort.

Consider the Vaillant 938 heat store combi, a cracking machine with very good rates of DHW flow. They've got 2x 7.5L hot water storage tanks in an insulated jacket at the rear of the boiler, which gives DHW outputs similar to an unvented cylinder. They stick out a bit, so check you have the depth ( basically it's a 837 combi mounted onto the jig which houses the tanks ). Have had two 'OK' showers running off one of these, also where the mains pressure was very good / high. Plumbed a dedicated 22mm cold mains feed direct from the stopcock to the 15mm inlet at the combi for max results. Would be perfect for you unless your DHW demand is normal / low eg 'OK' showers vs a decent blast!?

[NewToAllOfThis]

Thank you for the replies, starting to understand what I should be making sure is agreed with the plumber. The boiler will be in a very small area so not sure if the 837 will be a bit too big. I think the shower has a maximum throughput of 15 ltr/min and we are likely only to have one running at a time so could I get away without having a storage tank?

 

We have temperature controlled mixer showers but the taps to sinks are standard mixer taps, does the pressure from hot and cold feeds into the taps and shower have to be at the same pressure to stop the water being forced back down the pipe from the higher pressure feed. 

 

What is the benefit of having the WC's at higher pressure, will they take a lot longer at 3 bar than 4 or doe it stop a problem with toilet being flushed when someone is showering.

 

I've noticed that I need a Double-Check Valve on the mains inlet, would this go between the mains inlet and Stopcock or after the stopcock, and where should the Y strainer that JohnMo mentioned.

 

Any nice diagrams floating around showing layout for how all the bits go together.

[Temp]

If the pressure is too high for the boiler it will need one where it enters the house. I would set that quite high.

 

I would also put pressure reducers on the basin taps to avoid/control splashing.

 

Make sure they are accessible as I find they need adjusting every few years to increase the pressure slightly.

Edited October 18, 2022 by Temp

[JohnMo]

I put my strainer immediately upstream of the prv.

 

Stop cock, check valve, outside tap, strainer, prv to the house.