Flow and return mixed up

[diy_dave1978]

Hi,
I'm not a plumber or tradesman.

I've just had a new Ideal logic c30 combi boiler fitted that replaced a very old Baxi system boiler. TRVs were also fitted.

I asked the installer which pipe was flow, and which was return (so that a magnetic filter could be added later). He said when looking at the boiler, the return was on the left. Flow on the right. He added a drain of to the left pipe.

However, when feeling which pipe gets hot first, the left does. The radiator pipes get hot on the lock shield side first. The user manual says left is flow.

It seems its backwards to his intention.

Could someone answer the following?

1. Does it matter?
2. I was told by chance that the TRVs they fitted (bulldog?) would work on flow or return side, but they fitted them on the side which had a "wheel". I guess the intention was the flow side.
3. Is the drain off affected?

Many thanks.
Dave.

 

[ianmcd]

Dont worry too much, most modern TRVs are Bi-Directional , even if they were not the only real worry would be noise nuisance, older TRVs if orientated wrongly would be noisy when trying to close down, drain off wont make any difference,the magnetic filter should be fitted on the return near the boiler if possible when you get around to installing it.

 

[diy_dave1978]

Thanks ianmcd.
I aim to swap out the old radiators at some point soon so I will switch the TRVs then, and add the filter to the return near the boiler.

 

[ianmcd]

Thanks ianmcd.
I aim to swap out the old radiators at some point soon so I will switch the TRVs then, and add the filter to the return near the boiler.

No need to switch the TRVs, as said if they are modern ones they should be fine regardless what end they are on, some need setting, no tools needed just done with your fingers, not sure which ones you have but google the installation instructions and they will tell you if you need to do anything

 

[dilalio]

And you don't really want to stick TRVs on the side of any rad that is in the corner... You want it on the side that is into the room to get better response to the average room heat.

 

[diy_dave1978]

I think they are bulldog 2. The installers took the boxes away.

The technical guide for bulldog 2 doesn't mention setting to reverse.

Good point about having a TRV in the corner. I guess I will just leave them to be consistent.

Thanks everyone.

 

[Harry Bloomfield]

I asked the installer which pipe was flow, and which was return (so that a magnetic filter could be added later). He said when looking at the boiler, the return was on the left. Flow on the right. He added a drain of to the left pipe.

However, when feeling which pipe gets hot first, the left does. The radiator pipes get hot on the lock shield side first. The user manual says left is flow.

Doesn't that suggest the boiler might have been installed the wrong way around?

 

[ericmark]

I found with mothers house where the TRV was on return, the lock shield valve setting became critical, as the TRV sensor does not get warm until whole radiator is hot if too much flow, as to if this varies according to head used I don't know, I was using Energenie heads, which have both air and water sensors. I slowly reduced flow on lock shield until current reported temperature was not above target temperature, and once done they worked OK.

However out of preference would normally fit on supply side, there are exceptions, in my kitchen the return side is closer to the outside door, so in that case would fit on return side so the open window close down feature had more of a chance to work. Also using cheaper eqiva head in kitchen as no open window feature on the more expensive Energenie heads.

You need to use some common sense rather than try to follow rules, as things are changing so fast, it was not long ago when you did not fit a TRV in the room with the wall thermostat, but today TRV and wall thermostat can be linked, so that is no longer the case.

 

[diy_dave1978]

Doesn't that suggest the boiler might have been installed the wrong way around?

Yes. Is does to me. Personally, I think he has piped it up backwards, but I'm often too picky. I wouldn't have left it that way.

 

[Harry Bloomfield]

If its piped backwards, the boiler will not work properly, surely? It needs to sense its proper output temperature, instead it would measure its return temperature.

Easy check is to note which is supposed to be the boilers flow pipe from the manual, then fire the boiler from cold - the flow will be much hotter than the return. I always mark my pipes with an arrow, showing direction of flow on each pipe.

 

[Madrab]

If its piped backwards, the boiler will not work properly, surely?

I don't think it's the flow through the boiler that's swapped around rather the direction the wet central heating system is running. It's a combi boiler with an internal pump and diverter so that will flow properly and there are no external pumps or 2/3 port valves to get in the way. The actual central heating system can run in either direction, as long as the TRV's are bi-directional.

 

[ianmcd]

See it on a daily basis, with the Eco Scheme and the throw a boiler at the wall in half a day brigade, they couldnt care less if it is reversed, as long as the water circulates, the boiler doesnt know where it is going and coming from, as already stated only the TRVs can be affected as long as no non-return valves have been fitted before new boiler installed

 

[Harry Bloomfield]

Surely they would have a flow temperature sensor fitted, every boiler I have had since the 80's had one? If it sensed the return in error, it would constantly trip the over- heat stat.

 

[ianmcd]

Surely they would have a flow temperature sensor fitted, every boiler I have had since the 80's had one? If it sensed the return in error, it would constantly trip the over- heat stat.

you are over thinking it, the circuit is simply a coil, the flow will leave the boiler from the boiler flow and return to the boiler via the boiler return, no sensors will be affected

 

[Harry Bloomfield]

you are over thinking it, the circuit is simply a coil, the flow will leave the boiler from the boiler flow and return to the boiler via the boiler return, no sensors will be affected

Then why would boiler manufacturers go to the trouble they do, to mark up flow an return pipes? The flow pipe will be much hotter than the return, that is the whole purpose of the boiler.