New boiler installation problem

[gasandoilman]

pics ok and pipe work not to bad i would not have a 3port valve with a gate valve(red stop cock) to slow or stop heating upstairs i would have an s plan +(3 div valves) just better control of zones..

The bit we need to see was the return pipe meeting the return heating..
think this will be covered under the floor upstairs.
He should have brought the primary(h/w) return down and joined nearer the boiler as when you have hot water on the water goes up the return pipe of heating into the rad.
Suppose he could fit a non return valve on heating returned stop this but it should have been piped properly in the firs instance

 

[doitall]

Having any motorised valve/s will not prevent reverse circulation if it has been piped up incorrectly.

If there's no return path via the flow then reverse circulation is not possible.

The easiest way to check is to run the heating as normal and mark all the flows into the radiators by feeling the pipes, when you turn the heating off, the other end will get hot first.

I should also add, this may be an existing problem that didn't show/matter if the primary circuit was gravity.

 

[Duh]

Sorry that I can't provide anymore pics, that is, without tearing floorboards up, or dismantling the stairs - and it's so long since I've had the vitality to even think of doing anything like that...

I'm all out of further information I'm afraid.

You've all been very helpful, many thanks.

 

[doitall]

As I said turn the heating on and feel which pipe gets hot first on the problem radiator. then let it cool.
Finally turn the hot water only on and check the pipes again to see if the other end is now getting hot first.

 

[gas4you]

If there's no return path via the flow then reverse circulation is not possible.

If the returns are pipe up incorrectly then you could get reverse flow to the heating when the HW is selected.

I've even known a rad to get hot with ther circulation just in one pipe. It appeared as if the hot was going up the middle and the cooler water was returning around the edge.

God knows how this happened but it did

 

[doitall]

If there's no return path via the flow then reverse circulation is not possible.

If the returns are pipe up incorrectly then you could get reverse flow to the heating when the HW is selected.

I've even known a rad to get hot with ther circulation just in one pipe. It appeared as if the hot was going up the middle and the cooler water was returning around the edge.

God knows how this happened but it did

With larger pipes you can get parastatic circulation where the water circulates within the same pipe, it can also do this with smaller vertical pipes but not usually a problem

 

[Duh]

Hi Guys

I ran the 'Heat hot water' cycle for 5 minutes, and had a manic time under the stairs - sticking red and blue stickers on pipes.

From this, I was able to print off my last pics of pipes, and colour them in - inexpertly - need a 3 year old - red pipes hot, green pipes still cold.

You'll be able to see from the pics that I've used a highlighter pen (yellow edged black) to point to 3 areas where pipes meet, and where hot meets cold. Confused? You will be.

You can access the pics at my album 'Duh', file 'colour coded pipes'.

Hope that this makes the mud a little clearer...


Again, see
//www.diynot.com/network/Duh/albums/
Mod10

 

[ChrisR]

One way that reverse circulation can happen:
Blue is circulation you want, red you don't.
Red is in parallel with the purple, so most water goes down the purple, but not all.

 

[Duh]

That's a great diagram, and I've printed it off.

Thanks Chris.