10l under sink wate heater (ATC)

Fluppen

Hi, I am replacing an under sink water heater. Old 10l ATC with new 10l ATC. When I bought it I assumed I could just replace one with the other but reading the instructions has shown that is not the case. I'm very used to plumbing water troughs and outdoor taps but they don't come with warranties and safety warnings
The old one had what I think looks like a pressure release and non return valve combined fitted directly on the cold water inlet. The new one according to the instructions requires a separate pressure relief valve and I think also a non return valve. For this there are distance requirements which as far as I understand it can't be met with the current pipework in place as the heater is located in the kitchen where the main water feed comes up through the concrete.
1 metre of pipe from the heater there is a splitter on the main inlet which feeds the cold water for dishwasher, cold kitchen tap, cold in for water heater, about 5 metres back this pipe feeds the rest of the house and the pipe continues outside to a water trough. Feed is from my own well which is about 200 metres away on the other side of the yard so plenty of distance there if that is relevant, pressure tank in the pump house retains pressure for the house.
Do I need to install an expansion vessel or am I misunderstanding the 2.8m distance requirement? Can I install the pressure relief valve within 1 m of the heater? can I install the non return valve within 1m of the heater? Do I need both?
I'm not a plumber and not trying to be but it is hard to get someone out for a small job like this when you live rurally, and I prefer t have as few people in the house as possible at the moment too. So I'm doing this myself and would like to do it the right way but also the cheapest and easiest way.
Thanks in advance for any advice.

Fluppen

Fluppen wrote: »

Hi, I am replacing an under sink water heater. Old 10l ATC with new 10l ATC. When I bought it I assumed I could just replace one with the other but reading the instructions has shown that is not the case. I'm very used to plumbing water troughs and outdoor taps but they don't come with warranties and safety warnings
The old one had what I think looks like a pressure release and non return valve combined fitted directly on the cold water inlet. The new one according to the instructions requires a separate pressure relief valve and I think also a non return valve. For this there are distance requirements which as far as I understand it can't be met with the current pipework in place as the heater is located in the kitchen where the main water feed comes up through the concrete.
1 metre of pipe from the heater there is a splitter on the main inlet which feeds the cold water for dishwasher, cold kitchen tap, cold in for water heater, about 5 metres back this pipe feeds the rest of the house and the pipe continues outside to a water trough. Feed is from my own well which is about 200 metres away on the other side of the yard so plenty of distance there if that is relevant, pressure tank in the pump house retains pressure for the house.
Do I need to install an expansion vessel or am I misunderstanding the 2.8m distance requirement? Can I install the pressure relief valve within 1 m of the heater? can I install the non return valve within 1m of the heater? Do I need both?
I'm not a plumber and not trying to be but it is hard to get someone out for a small job like this when you live rurally, and I prefer t have as few people in the house as possible at the moment too. So I'm doing this myself and would like to do it the right way but also the cheapest and easiest way.
Thanks in advance for any advice.

Starting with your isolation valve working towards the heater you may need a pressure reducing valve if it’s over 3 1/2 bar ish (the instructions will tell you the maximum inlet pressure value) then a non-return valve(this stops the hot water flowing up the cold pipe if someone opens a cold tap) then your expansion vessel (as close as is practical to help reduce possible noise issues) lastly your 6 bar safety valve that has copper pipework that then terminates in a safe manor, also try and stay away from plastic pipe it can turn to jelly in certain situations.

Fluppen

Thanks. Can I put in some extra length of flexi pipe to give me the 2.8m of pipe and avoid using an expansion vessel or is that just silly?

Fluppen

Fluppen wrote: »

Thanks. Can I put in some extra length of flexi pipe to give me the 2.8m of pipe and avoid using an expansion vessel or is that just silly?

You can, others have done before you but I would fit a 2 ltr expansion Vessel for a quiet life.

Fluppen

gary71 wrote: »

You can, others have done before you but I would fit a 2 ltr expansion Vessel for a quite life.

Thank you, much appreciated.

John.G

Fluppen wrote: »

Hi, I am replacing an under sink water heater. Old 10l ATC with new 10l ATC. When I bought it I assumed I could just replace one with the other but reading the instructions has shown that is not the case. I'm very used to plumbing water troughs and outdoor taps but they don't come with warranties and safety warnings
The old one had what I think looks like a pressure release and non return valve combined fitted directly on the cold water inlet. The new one according to the instructions requires a separate pressure relief valve and I think also a non return valve. For this there are distance requirements which as far as I understand it can't be met with the current pipework in place as the heater is located in the kitchen where the main water feed comes up through the concrete.
1 metre of pipe from the heater there is a splitter on the main inlet which feeds the cold water for dishwasher, cold kitchen tap, cold in for water heater, about 5 metres back this pipe feeds the rest of the house and the pipe continues outside to a water trough. Feed is from my own well which is about 200 metres away on the other side of the yard so plenty of distance there if that is relevant, pressure tank in the pump house retains pressure for the house.
Do I need to install an expansion vessel or am I misunderstanding the 2.8m distance requirement? Can I install the pressure relief valve within 1 m of the heater? can I install the non return valve within 1m of the heater? Do I need both?
I'm not a plumber and not trying to be but it is hard to get someone out for a small job like this when you live rurally, and I prefer t have as few people in the house as possible at the moment too. So I'm doing this myself and would like to do it the right way but also the cheapest and easiest way.
Thanks in advance for any advice.

Re your old combined PRV and NRV fitted directly on the heater, it actually was/is a combined PRV and anti syphon valve so the hot water could actually expand back through the anti syphoning valve and back through the cold mains and as long as the nearest cold draw off is > 2.8M away then the expanded hot water will not issue from any cold tap if opened.

Its a little strange IMO the way the (new) instructions are worded, the impression I get is that what they are saying that a expansion vessel is not needed (for10L) but the NRV is and must be located 2.8M from the heater. I would be pretty certain that if this is done then the PRV will lift every time the water is heated as the expanded water has no where to go, if no NRV then it is allowed to expand back through the mains, the 2.8M is (as stated) so as that hot water doesn't issue from any cold tap if located within this distance.
So I would suggest that a expansion vessel has to be installed to prevent the PRV lifting if a NRV is installed but not if the nearest cold water draw off is > 2.8M away and no NRV is fitted which is basically the way of your last installation but you will now be installing a far better type of PRV and could be at/near the heater.