Head wrecker!

[zeebeedee]

Got a row of 6 houses on my contract all new builds. Worcestor greenstar r28 he system http://www.acwilgar.co.uk/Boiler-Manual-PDF/Worcester Bosch/GreenStar 28 HE System.pdf

Problem is radiators in the back of the house only get Luke warm unless you turn the front off. There is a gate valve fitted acting as a bypass just after the return out the cylinder. This has some affect but not much. Today I worked out that if its on heating only the rads heat up fine, select both heating/hot water and the rads at the back of the house go Luke warm until the hot water is satisfied.

Pumps fine, system is balanced, no sludge clean as a whistle, what the hells going on????? The best theory I can come up with is the system layout, possible one pipe system to the rear of the property.

 

[GasmanxxxR1]

would be better having auto bypass, perhaps under sized pipework at the back

 

[tamz]

Fit an auto bypass and a balancing valve on the hw return.
Balance the system again while the hw is on.
Won't be a 1 pipe on a new build.

 

[lame plumber]

as mentioned probably undersized pipework to back

 

[zeebeedee]

Fit an auto bypass and a balancing valve on the hw return.
Balance the system again while the hw is on.
Won't be a 1 pipe on a new build.

Balancing valve?

 

[heliotrope]

Unlikely that the gate on the cylinder return is a bypass.

More likely to be a throttling/balancing valve. Turn it off then call for heating and hot water.
Gradually open the gate valve until you get heat at the flow.

Now check if the cooler rads are getting warmer.

 

[zeebeedee]

What you mean by throttling valve?

 

[Billy Bob Bob]

What you mean by throttling valve?

turn it down you numpty :yesnod:

 

[heliotrope]

Throttling valve will restrict the flow through the primary the same as a lockshield
on a radiator. So will let more flow to the further rads.

 

[zeebeedee]

Throttling valve will restrict the flow through the primary the same as a lockshield
on a radiator. So will let more flow to the further rads.

Turning the gate valve completely off has very little effect though. It was the first thing I went for after ruling out the pump/sludge.

 

[lame plumber]

look at the pipe runs then

 

[plumber0808]

Is the problem on the 6 houses or only 1?
Sounds like pipework is undersized or if its microbore it may be too long of a run from the manifold.

 

[Toxic Ted]

I think the systems have an internal by-pass so this could be worth a look

 

[TFGplumbing]

I had a job like this; last 2 rads on the system luke warm, and it turned out that the 3-port valve was faulty and Custard was getting hw & heating at the same time (they thought it was normal)

 

[zeebeedee]

Is the problem on the 6 houses or only 1?
Sounds like pipework is undersized or if its microbore it may be too long of a run from the manifold.

Every house! Some worse than others this ones the worst offender , back on Monday so ill take some boards up and look at the pipe work