Zoned central heating problem

[happyflyer]

Fred,

At this rate you will soon know more than me...:rockon2:

 

[fredfat]

yes its a sealed system with filling loop and he did show me how to use it briefly! So just to clarify the flow will be split some where to feed the 2 zones independently ? cheers

 

[fredfat]

I doubt that . My worry is that I might have more knowledge than the chap i hope is going to make it work haha

 

[plumber0808]

It's a pipework problem, if they have had the same problem before then they are getting it wrong every time.
Why fit the 2 port on the return? Boiler flow on to bypass on to 2 port valves one feeding down stairs one feeding upstairs.
the return should have one circuit for downstairs one circuit for upstairs teed in together close to the boiler.

 

[fredfat]

Hi Plumber0808 and thanks for your reply. Since they haven't fitted the valves in the flow side even if they have at some point split the flow into 2 how does the heated water not run through all the rads ? please excuse my ignorance if this doesn't make sense

 

[doitmyself]

I have checked the motorised valves and I think they are working, based on the return pipe of the zone that is turned off being cold.

Is the return pipe cold on both sides?

It sounds as if there is convection circulation in the zone which is turned off: not surprising with the zone valves on the return!

It might be worth checking that the zone valves are the correct way round (arrow on the side of the brass body, or IN at A, OUT at B).

 

[happyflyer]

 

[happyflyer]

This should help, it may not be exactly like this but this, there is always a chance that gravity circulation can take place even if the valve is shut on one circuit, especially upstairs, there is a way around this the installation of a loaded none return valve, its probably getting a bit too much after all we are in the trade, but the plumber from hell should put it right and stop gabbling about the number of rads on the system

 

[fredfat]

Hi doitmyself, thanks for your reply. the return pipe on the zone that is switched off is cold directly before the valve.The return pipe of the zone that is switched on is hot before valve. After the valve the 2 pipes return into a single pipe going back to the boiler and this pipe is also hot.

The zone valves are both facing in the right direction. many thanks for your help

 

[doitmyself]

there is a way around this the installation of a loaded none return valve,

I know that's the solution for reverse circulation, but would it work for the OP's problem? The valve would have to be fitted to allow circulation when the zone is open; and there could easily be enough pressure from the pump to open the valve.

 

[happyflyer]

zxzzxzxz

 

[fredfat]

cheers happyflyer that drawing is great it helps me understand what you was saying about the auto bypass, and explain what i think could be a problem.If the returns of the upper and lower floors are joined together before they reach the valves would this cause the problem ? I'm pretty sure that 2 of the downstairs radiators are joined to the upstairs return. Anyway cheers for all your advice I will report back as to what waffle I get on Monday.

Can i just ask one question re: the drawing.At the split is the idea that the heated water will only flow to the zone/zones that are switched on due to being pumped/pulled and no heated water should go into the zone that is not switched on ?

 

[happyflyer]

Another version but not showings auto bypass which the system must have, but less chance of cravity circlation when one vavle is open and one valve closed, hope you can understand all of this, you plumber won't.

Tony

 

[happyflyer]

I will do you a few drawing of whats going on in the system give me some time OK

 

[happyflyer]

You will see that if one valve is closed 1st floor and the other is open the flow rate and resistance in the system will change, as the 1st floor valve closes the bypass valve should start to lift causing the excess pressure to be absorbed and more water will go around the bypass loop, you need to understand that plumbers balls are not made out of glass and a lot of this is two hands on the pipe and an ear on a hammer not very assuring but that's how it is, saying all that your system should work, you never did say is there a bypass valve , in your case it must be automatic not just a gate valve

 

[happyflyer]

Automatic bypass valve should look like this

 

[fredfat]

Hi Happyflyer ,

Thanks for all your time and help. Sorry I didn't reply but got called away.

My system looks very much like your first drawing minus the bypass valve part. I cant see that anywhere. However on reading the boiler manual it says there is an automatic bypass inside the boiler, but then goes on to say if the system employs thermostatic radiator valves on all radiators, or two port valves, then a bypass circuit must be fitted with an automatic bypass valve to ensure a flow of water should all valves be in the closed position. Which means you where spot on!

Is there anywhere this could be installed that i would be able to miss it i.e under floor boards or would it be as it appears in your drawing?

One final question does the size of the pipe increase/decrease the pressure? the reason i ask is that it has been installed using a 10mm plastic pipe which seems very narrow compared to the copper pipes coming from and to the boiler.

Many thanks for your help

Fred

 

[jam1979]

why dosent your plumber put the zone valves on the flow and piece the pipes back on the return

 

[happyflyer]

Hi Happyflyer ,

Thanks for all your time and help. Sorry I didn't reply but got called away.

My system looks very much like your first drawing minus the bypass valve part. I cant see that anywhere. However on reading the boiler manual it says there is an automatic bypass inside the boiler, but then goes on to say if the system employs thermostatic radiator valves on all radiators, or two port valves, then a bypass circuit must be fitted with an automatic bypass valve to ensure a flow of water should all valves be in the closed position. Which means you where spot on!

Is there anywhere this could be installed that i would be able to miss it i.e under floor boards or would it be as it appears in your drawing?

One final question does the size of the pipe increase/decrease the pressure? the reason i ask is that it has been installed using a 10mm plastic pipe which seems very narrow compared to the copper pipes coming from and to the boiler.

Many thanks for your help

Fred

Fred,

If there is no bypass valve on the system then when say the 1st flr valve is closed and the GF open the system pressure will be higher and there will be a tendency for the pressure to try to push against the sparing in the valve that is closed, hydraulics are not simple, I did ask you what the pump is set at and its probably in the boiler case so you can't get at it. He needs to fit a proper bypass valve, I will have a look at the boiler instructions did you tells what the boiler was

 

[happyflyer]

Fred page 9 of Installation Instruction


Boiler Control Interlocks
Central heating systems controls should be installed to ensure
the boiler is switched off when there is no demand for heating, in
compliance with Building Regulations.
Heating systems utilising full thermostatic radiator valve control
of temperature in individual rooms should also be fitted with a
room thermostat controlling the temperature in a space served by
radiators not fitted with such a valve.
When thermostatic radiator valves are used, the space heating
temperature control over a living / dining area or hallway having
a heating requirement of at least 10% of the minimum boiler heat
output should be achieved using a room thermostat, whilst other
rooms are individually controlled by thermostatic radiator valves.
However, if the system employs thermostatic radiator valves on all
radiators, or two port valves, then a bypass circuit must be fitted
with an automatic bypass valve to ensure a flow of water should
all valves be in the closed position.



Fred,

My English is poor but this is what they should have said

or two port valves, then a bypass circuit must be fitted
with an automatic bypass valve to ensure a flow of water is maintained within the boiler, should
all valves be in the closed position.

Tony

PS I have noted the pump is in the boiler case to stop people adjusting it, how sad is that, its not a hanging offence to adjust the pump, never mind the buzzcocks 😛unk: