Using Balanced cold

[Mgrant]

Hey, do people tend to use the balanced cold connection on unvented hot water systems. To feed all the cold supplys on a house,bar the kitchen sink tap which is taken straight of the mains. Or is balanced cold not often used? I often see it just capped off on the composition valve in the cylinder cupboard.

 

[Best]

Telford require a double check valve on the hot outlet on jobs where one or more cold outlets are not balanced.

 

[Best]

Old mixers connected with gravity hot & mains cold had to have back feed to some extent if mains pressure was decent & no check valves fitted. Just nobody notices.
Old mixers mostly mix in the body before going into single piped spout.

 

[chris watkins]

Old mixers connected with gravity hot & mains cold had to have back feed to some extent if mains pressure was decent & no check valves fitted. Just nobody notices.
Old mixers mostly mix in the body before going into single piped spout.

Perhaps you have different taps over there but we have divide flow & have had for a very long time, so hot & cold are kept separate. They only mix when they leave the spout, so no back flow & no requirement for check valves.
It is only the cheap imported taps which mix in the body & cause all these problems.

James1 - I would strongly recommend that all the cold's to mixer taps & showers (not the kitchen sink, see above) are taken from the balanced port or if that is not possible on an existing system then install a dedicated pressure reducing valve on the cold.
We have so many problems with back feeding from the higher pressure cold to hot. Even if check valves are installed they break.

 

[Best]

Perhaps you have different taps over there but we have divide flow & have had for a very long time, so hot & cold are kept separate. They only mix when they leave the spout, so no back flow & no requirement for check valves.
It is only the cheap imported taps which mix in the body & cause all these problems.

Lol! No we are in the 21st century here & are same as rest of UK - modern mixers are all separate flows here, but there are thousands of mixers that are not dual flow still around & some I know for a fact were being sold within the last 20 years.
One thing I would say about a plumber not using a balanced mains supply to the kitchen sink is - what if that mixer or a later mixer is faulty & water passes through the body? Still better ideally that it is balanced cold for that reason.

 

[Mgrant]

If balanced cold wasn't used and problems occurred could a pressure reducer be put on the cold mains and set to 3.5 bar so its the same as the hot pressure.

 

[Ermintrude]

Not really going to work, cold may fluctuate and 3.5 is max it could be right down at 1.5. Might have to be a suck it and see, start at 1.5 and work upwards on prv

 

[sheff paul]

Hey, do people tend to use the balanced cold connection on unvented hot water systems. To feed all the cold supplys on a house,bar the kitchen sink tap which is taken straight of the mains. Or is balanced cold not often used? I often see it just capped off on the composition valve in the cylinder cupboard.

Normally 1st fix so the kitchen tap and outside tap are on mains,take a 22mm straight to the cylinder cupboard,or have a separate prv under the sink.James 1 this is a good intelligent question,shows you are thinking

 

[chris watkins]

Not really going to work, cold may fluctuate and 3.5 is max it could be right down at 1.5. Might have to be a suck it and see, start at 1.5 and work upwards on prv

Surely even if cold mains is less than the PRV serving the hot it will still be the same ??
The hot is often at a greater pressure than the cold system due to expansion when it is heated.

 

[chris watkins]

If balanced cold wasn't used and problems occurred could a pressure reducer be put on the cold mains and set to 3.5 bar so its the same as the hot pressure.

Yes, that should work.

 

[Ermintrude]

What I was trying to say was it might be difficult to set up. Start off with prv set at 1.5 on cold 3 on hot and see what it's like, if ok climb up to 2 and 3 and 3.5 over a few weeks?

 

[sheff paul]

Surely even if cold mains is less than the PRV serving the hot it will still be the same ??
The hot is often at a greater pressure than the cold system due to expansion when it is heated.

noticed when I was commissioning last week the hot does come out a bit quicker than cold

 

[voivod]

When was on sites (5 years+ ago) . We had drawings from the cylinder / heating manufacturers.
They used to ask us to fit a prv at sink 3bar ...then you had the prv which came with the cylinder aswell .
Some asked for full pressure to cyl prv and a seperate prv for colds
And some wanted the cylinder prv under the sink with a seperate balanced draw off for cold and another pipe from the prv to the cylinder.
All combis got a prv on incoming mains too.
In edinburgh have seen mains at 6/7 bar so think is a good idea
( which is also handy when we were pressure testing the systems up to 10 bar.,, loads less pumping )

 

[kay-jay]

good practice to use a balanced cold supply, even if there are no mixer showers or taps as there may well be in the future. if its not a new build and there would be a lot of upheaval lifting floors and whatnot then i would whack an additional prv under sink.

 

[Mgrant]

So are you saying if possible on a new build to have the cold mains enter were the cylinder is located in the house and have the houses stop tap there. As apposed to the usual place of under the kitchen sink. Feed the cylinder off this, then take all the cold supply's to the house from the balanced cold connector on the cylinders composition valve.

 

[kay-jay]

So are you saying if possible on a new build to have the cold mains enter were the cylinder is located in the house and have the houses stop tap there. As apposed to the usual place of under the kitchen sink. Feed the cylinder off this, then take all the cold supply's to the house from the balanced cold connector on the cylinders composition valve.

No. Stoptap on entry as per regs. Then pipe to cyl cupboard and take a balanced cold to oitlets