Flow and Return mix up?

[piper64]

In 2011, I had a new combi boiler installed to replace an old back boiler and now have concerns that the flow and return were mixed up. The existing pipework was untouched except for a short length of the main 22mm pipes from the back boiler. All rads except the bathroom have TRVs on them.

Story below, if you want to read it, but my question is.....if it is mixed up, what are the implications for the system. The water is entering the rads from the wrong end isn't it?

It 'works' but I have never felt is worked properly since the combi install. EG: Some rads stay hot, even when the TRV is turned right down, which I blamed on faulty valves. Some don't get hot when they should.

I realise I should get the fitter to come back, but after 5 years he wouldn't admit or remember doing anything wrong.

I can get the pipes at the boiler swapped over I know, but I can't help thinking that my investigations are flawed...I'm not a plumber or heating engineer.

Before I get someone out, am I correct in saying that the pipes that would get hot first are the 'Flow'? Is there another way to test the pipework, seeing as I can't visually check the routing under the floors without wrecking the house.



Story:
At the time as the boiler, two new rads were installed, to replace existing ones.
Since then, I have put in two new radiators myself, again just replacing old ones, so all I did was put the TRV on the same side as the existing.
I am now in the process of replacing another radiator for a new one and noticed that the return side pipe got really hot, way before the flow pipe, even though I just replaced new for old, same set up. Two rads downstairs at the end of a run dont get hot at all, but the 'Return' pipe does.

I've looked at as many pipes as I can see and the fitter has written 'H Return' on what I am convinced is the 'Flow' pipe. Following this pipe back to the boiler it does in fact go to the 'Flow' side, NOT the 'Return' as he seemd to believe. Firing up the heating makes this 'H Return' pipe get very hot, very quickly, so it clearly is the 'Flow' pipe.

 

[Agile]

It makes no difference which way round a rad is connected.

You have done several DIY rad jobs and clearly the system is no longer balanced.

So at next boiler service time get the engineer to balance the rads for you.

I would be interested to know how you initially found the hot water from the combi compared with the previous cylinder fed supply?

Tony

 

[piper64]

Hi Agile
I don't wish to sound disrespectful and I'll take your word, but I can't understand why it makes no difference because I always gathered that the rad 'called' for hot water via the TRV. To me, the system at present is drawing hot water through the 'wrong' end of the radiator and I can't fathom out why it doesn't matter.

It's due a service soon, so I was planning on getting my moneys worth and asking him to sort out the heating too while he was there, which is why I was concerned about what I saw as a 'mix up'.

Regarding the HW from the combi, I'm not sure what you mean except I can now draw off HW when I like, rather than trust that my offspring had left me enough in the cylinder, which invariably they didn't so I'd have to switch on the immersion heater! The only drawback is that the shower pressure gets affected if a hot tap is turned on, but not enough to bother about and I'm sure the pressure is better than it was with the old boiler...no need for a power shower pump.

 

[ianmcd]

would not make any difference as to how hot the radiators get if the flow and returns were mixed up, if you had single direction Thermostatic radiator valves you might get a noise nuisance as the valves tried to close nothing else

 

[piper64]

Hi Ian, So no need to swap the 22mm F and R pipes over at the boiler then? Just that I was reading a few posts elsewhere on this forum about fitters having to sort out heating and boiler issues by swapping the F and R over as they were fitted the wrong way in the first place.

How do I check if they are bi directional or one way TRVs? Does it say anything on the valve? They are a mix of brands from merchants, the fitter and the latest is from Wickes.

 

[Razor900]

There will be an arrow on the body of the valve showing the flow direction. On bi directional valve it looks like a capital L with arrowpoints on the ends

Sounds more like crap TRV's or a balancing issue to me

 

[piper64]

Just had a look around and they are mostly marked with the 2 arrows, except a really old one on a radiator which is going to be changed soon, it's only got 1 arrow pointing toward the radiator ( opposite direction to flow).The bathroom one doesn't have a TRV.
Around the house it's a mix of Reglo, Drayton, Bulldog, Wickes and ECA valves as well as the old no name one. A couple of the Reglo ones don't seem to have any marks clearly showing, but another one of exactly the same brand and age does, so I'm assuming they are the same.
I'll get the system balanced and see what happens, but I suspect that the old one will cause an issue if it's not bi directional and I will have to get all it done again when the rad gets replaced.

So, the concensus is that the heating will work just as well with the TRVs fitted either way to the flow? Still seems odd to me....

 

[gasmanstu72]

the direction of the flow through a radiator has no consequence, the only trouble you'll have is a noisy TRV if it's on the wrong way and not of the bisexual variety
and you'll only find this out when it starts to shut down,

 

[ianmcd]

all a TRV does is stop the water flowing when the room gets to the temperature that the sensor is set at , it doesnt matter which end it stops the flow, the only problem you get is some valves if single directional will chatter when trying to close and cause a noise nuisance, which can be quite dramatic at times

 

[just pumps]

The direction is important on a column rad though I believe.

 

[just pumps]

Hi Ian, So no need to swap the 22mm F and R pipes over at the boiler then? Just that I was reading a few posts elsewhere on this forum about fitters having to sort out heating and boiler issues by swapping the F and R over as they were fitted the wrong way in the first place .

Think you will find this is about the pipes being the wrong way round at the boiler.

 

[piper64]

Hi chaps, all's fine with the set up 'as is' then which is good.

@just pumps...that was my original concern. The 'flow' pipe at the boiler is marked by the fitter as 'H Return' a few feet further on? This pipe is actually the 'Flow'. Is this different to the posts that I read?

 

[just pumps]

Sorry piper I don`t know which posts you`ve read, easy way to find out is to shut the boiler down then when all pipes are cold see which one gets hot the quickest OR just trust the guy doing your service.

 

[piper64]

The pipe that gets hot first is the one marked H Return, so is actually the flow pipe and I can trace it back to the 'flow' outlet on the boiler, but that's why I'm confused when I read the posts about pipes being the wrong way around at the boiler. From what I gather now, there is no right or wrong, it's just flow and return?

I'm happy to trust the service chap, but not the original fitter!

 

[motorbiking]

It does make a difference in my opinion..
- some rads are designed for the water to flow in one direction, typically if you connect the wrong way round, it can take more time bleeding them, but that is about it.
- most TRVs are meant to go on the flow and they can make a hammering sound if they are on the return. They are also less efficient at shutting off

one option is to slow the pump speed down, so that the water flows more slowly, this can improve circulation, but will mean the rads take a bit more time to get hot.