S plan heating system

[Glengormless]

Hi guys. Just a quick question as to the install of this system. If the boiler is fitted downstairs and the cyclinder and valves upstairs does this mean that 4 pipes have to be run upstairs with regards to heating?. Central heating flow, Central heating return, Hot water return( to tee in after all downstairs radiators have been connected ) and another central heating flow to feed downstairs. I realise that if a third valve was fitted downstairs it could be zoned and have no need for the fourth pipe( 2nd ch flow). Is this correct?. Thanks for the help

 

[kirkgas]

having zone valve or not doesnt effect or cause reverse circulation, most of the time the problem happens in the following scenario: boiler downstairs cylinder upstairs in bedroom cupboard with bedroom rad further in the room, on hot water only the water comes back down the return, comes out the cupboard and down to the branch of a a tee where the cylinder and rad circuit join together, the water simply goes right and left and up the return into the rad via the lockshield valve, it is easy to connect it this way, but the correct way is to run a return pipe from the rad back to the circuit in the hall, and too run a seperate dedicated return from the cylinder ALL the way back and connect it after the downstairs circuit, some have spilt the difference and connected the hot return half way down, but even then it can cause reverse flow through the nearest downstairs rad

 

[diamondgas]

having zone valve or not doesn't effect or cause reverse circulation, most of the time the problem happens in the following scenario: boiler downstairs cylinder upstairs in bedroom cupboard with bedroom rad further in the room, on hot water only the water comes back down the return, comes out the cupboard and down to the branch of a a tee where the cylinder and rad circuit join together, the water simply goes right and left and up the return into the rad via the lockshield valve, it is easy to connect it this way, but the correct way is to run a return pipe from the rad back to the circuit in the hall, and too run a seperate dedicated return from the cylinder ALL the way back and connect it after the downstairs circuit, some have spilt the difference and connected the hot return half way down, but even then it can cause reverse flow through the nearest downstairs rad

I agree that your scenario is correct kirkgas however I'd have to disagree regards the zone valve. In your scenario, if you turned the radiator off that would stop the circulation yeh? In the same way if you has 20 radiators instead of one teed in as you describe, with a zone valve fitted and closed there would be no completed circuit for the water to 'reverse' through.
If the system is fully zoned, as in my first diagram post, you have in effect 3 separate zones. The cylinder could just as equally be a 3rd heating zone. Each one works independent of each other via zoning... none of the circuits would effect either of the others.

 

[ecowarm]

having zone valve or not doesnt effect or cause reverse circulation, most of the time the problem happens in the following scenario: boiler downstairs cylinder upstairs in bedroom cupboard with bedroom rad further in the room, on hot water only the water comes back down the return, comes out the cupboard and down to the branch of a a tee where the cylinder and rad circuit join together, the water simply goes right and left and up the return into the rad via the lockshield valve, it is easy to connect it this way, but the correct way is to run a return pipe from the rad back to the circuit in the hall, and too run a seperate dedicated return from the cylinder ALL the way back and connect it after the downstairs circuit, some have spilt the difference and connected the hot return half way down, but even then it can cause reverse flow through the nearest downstairs rad

I agree but the easiest way to remember is the hot water return must be the LAST tee to the boiler.
Eco

 

[kirkgas]

I agree but the easiest way to remember is the hot water return must be the LAST tee to the boiler.
Eco

i totally agree and am old enough to have been given the time to do it properly "in the good old days"

 

[kirkgas]

View attachment 2809 This or a variation of it which means 4 pipes yeh?

If I've missed something out I'm sure a more experienced installer will correct me. It's been a decade or more since I messed around under floorboards!

looks good and the way you have drawn it you can see it would have been a lot easier for you to simply join the hot water return into the upstairs circuit before it dropped downstairs, which is exactly what people started to do as they saved a length of 22mm and some time, but in some instances it caused one rad to reverse heat

 

[diamondgas]

looks good and the way you have drawn it you can see it would have been a lot easier for you to simply join the hot water return into the upstairs circuit before it dropped downstairs, which is exactly what people started to do as they saved a length of 22mm and some time, but in some instances it caused one rad to reverse heat

It use to cause whole systems or at least all of upstairs to heat kirkgas. Usually after an extension or additional rad had been added ... Down to differential pressures on the "upstairs" & "downstairs" return pipes causing secondary circulation... Solved with a strategically placed non-return valve, more times than i care to mention to be honest and usually after umpteen diverter valves had been fitted!! lol

 

[Inverness]

I have a problem. I have a s plan fully pumped seal system. I live in a bungalow. When I call for hot water only I get get radiators getting warm. The boiler has two Danfoss motorised valves beside it one for hot water and the other for heating. When I call for hot water The cylinder gets hot and so does the pipe after the heating motorised valve. Could this mean it's letting by?

 

[ShaunCorbs]

I have a problem. I have a s plan fully pumped seal system. I live in a bungalow. When I call for hot water only I get get radiators getting warm. The boiler has two Danfoss motorised valves beside it one for hot water and the other for heating. When I call for hot water The cylinder gets hot and so does the pipe after the heating motorised valve. Could this mean it's letting by?

yes depends on how old the valve is could do with a new one

 

[Inverness]

Nice one. I'm only in my second year of svq3 and I've got a homer I'm doing tomorrow for my friend. I've already purchased new Honeywell motorised valves as there are better quality. And I was thinking I might ask for a professional opinion first. I've done a drawing of the system and worked out the possibilities and this was the only one I could be sure of. Plus was round at the house and I felt the heating pipe after the motorised valve when I called for hot water and it was hot.
Thank you.

 

[ShaunCorbs]

np but next time create your own thread instead of bring one back to life, plz the mods like it that way