UFH flow and return switched intentionally

[Rubics]

Hello members, thanks for looking into this. I am confused onto why my pair of buddy plumbers have jointly and intentionally switched the manifold flow and return connections. Their initial response was due to space restrictions on the left hand side of the manifold which is no longer the case as there is more space available now to make it right. However, the insist the current installation is just fine and no need to do anything. Could someone help me understand what happens when the hot water output from the mixer pump is connected to the return arm (blue) of the manifold where the actuators are. As a result the water return from the under floor pipes are connected to the flow arm(red) of the manifold. I can see that they have connected  the pressure gauge on the return arm of the manifold as this is where the pump is feeding hot water.Wouldn't this setup hinder with the normal and efficient functioning of the actuators and the flow rate controllers? How do I explain this to the knowledgeable plumbers who installed it who think they are right and this current installation is just fine? What problems do you see with such a reversed connection? Please note they have only switched the output of the mixer pump to connect to the return arm of the manifold instead of connecting to the flow arm. In addition, there is no heat adjustments required on the actuators as its all ON or nothing across all zones. Thank you 

[Nickfromwales]

Hi.

For one, the flow gauges iirc will only register flow if the water is going into that rail, as the water pushes into the pipe loops there is a slider that gets drawn into the current and that pulls down the flow register in the gauge. As per your pic, the pump is running but the gauges aren't appearing to be doing anything?

 

The other thing, is that pumps are suppose to be mounted vertically, but that's just old school mentality from 30+ years of plumbing (I don't mount pumps any other way) so air can rise upwards with flow vs against it.

 

Also, as the boiler is only servicing UFH via a mixing valve, there should be a bypass, other than the one ion the boiler, so when there is pump overrun (the boiler pump is pumping faster than the UFH is consuming that flow/pressure) it can cycle back on itself. That promotes longevity of the boiler, and shouldn't be dismissed as 'unnecessary'.

 

Finally, does that gauge show 70^oC flow temp?!? Who commissioned this and what is the target/design flow temp that's supposed to be going into the floors?

[JohnMo]

Couple observations

 

You have a combi boiler, so that will have a recirculation pump, there is zero protection for that pump. It needs a min flow valve or connecting via a close coupled tee.

 

Would question the need for the pump and mixer on the manifold at all, it's doing nothing. Your boiler has a pump and temperature control, it could be direct connected. Run on either weather compensation or fixed flow temp and a thermostat switching the UFH on or off.

 

Basically as set up currently the flow through the system is reversed. It's a bodge. The pump and mixer can go either end of the manifold so that's not an issue, it just needs connecting the current way about. Or as above delete it.

 

Also missing is isolation valves between pump/mixer and manifold.

 

To fix it either the pump mixer assembly needs to set up correctly or delete it.

[JohnMo]

8 minutes ago, Nickfromwales said:

Finally, does that gauge show 70^oC flow temp?

Or would that be return temp? If so the flow could be circa 80 degs?

[Nickfromwales]

Just now, JohnMo said:

Or would that be return temp? If so the flow could be circa 80 degs?

That's the flow out of the pump.

[Rubics]

Hi Nick,

 

Thanks for your inputs.

 

The 70C is the flow output as its the output from the mixer pump. The plumber buddies (both qualified and gas safe) commissioned it together. Sorry, I am new to these terminologies and I am not aware of the target design/flow temp. I could ask my supplier and find out more details on what they have assumed. For me its only UFH for my new extension and anything beyond that is alien terms (but I am learning now as I am worried about how this is being handled). 

 

I do not know whether the flow gauges are doing anything as now the water is flowing in the opposite direction, my understanding is the gauge is no longer capable of doing its job.

 

Pump mounted upside down - I agree, and I dont know whether they will make this right if I request/demand them to make it right. Any suggestions are trashed highlighting the efficiency and modern parts of new boilers and how they can cope with such deviations

 

 

 

 

[Rubics]

Hi John, 

 

Many thanks for taking time to look into this

 

I will suggest them to look into this 'here is zero protection for that pump. It needs a min flow valve or connecting via a close coupled tee'

 

With regards to 'need for the pump and mixer on the manifold at all' - could this benefit from ensuring water pressure to feed 10 100m under floor pipes? It could be that the supplier gave it as a pack and the plumbers went on with installing it. I can see the benefit of saving electricity if the pump and mixer is not required at all. 

 

Could you elaborate this 'it just needs connecting the current way about'? Are you saying it needs to connected the other way - mixer output to the flow (red) arm? 

 

 

Your observation on 'missing is isolation valves between pump/mixer and manifold' - i remember seeing the isolation valves which the plumbers dismissed as there are no radiators and no possibility of dirty water entering the UFH pipes. One of the videos I watched yesteday had the isolation valves between the boiler and the mixer pump. Is this where you would recommend the isolation valves? Between the boiler and the pump/mixer and not between the pump/mixer and the manifold?

 

Many thanks

[JohnMo]

Before answering the questions what boiler do have? Make and model?

 

Also how many thermostats are you installing 1 or lots of them?

Edited Tuesday at 15:28 by JohnMo

[Rubics]

Its a brand new dedicated combi boiler just for the UFH. The make and model is Ideal Logic max combi(2) C24.

 

just one thermostat just to turn it on and off as the UFH is just serving two zones even though we have too many pipes. So its all pipes ON together with no distinction of zones/areas. Thanks

[Nickfromwales]

14 minutes ago, Rubics said:

Its a brand new dedicated combi boiler just for the UFH. The make and model is Ideal Logic max combi(2) C24.

 

just one thermostat just to turn it on and off as the UFH is just serving two zones even though we have too many pipes. So its all pipes ON together with no distinction of zones/areas. Thanks

The combi should have an integral bypass, but that should be a failsafe only.

 

WRT losing the UFH manifold pump and blending valve, I’m not so sure that’s a good idea as then you are at the mercy of the flow temp from the boiler. 
 

How long has the heating been on for, and do the floors feel warm/hot with flow going in at 70°C??

 

The hottest I’ve set these to in adverse conditions is about 45°C to get a floor surface temp of 24/25°C, and a room temp of 21°C. At 70° it should be like Barbados in there. How is this performing currently? 

[Rubics]

THanks Nick, 

 

I ran it for 10 hours and not much heat output (barely warms up the floor). The plumbers have agreed to make it right whilst keeping the manifold pump and blending valve. The flow rates need to be re-balanced. I can insist them to add the isolation valve as well.

 

Thanks

[JohnMo]

I would 

 

Add isolation valves between mixer and manifold

 

Correct the orientation of the pump and mixer.

 

Form a primary loop between boiler flow and return.

 

Use a close coupled tee to UFH pump mixer 

 

[Nickfromwales]

3 hours ago, JohnMo said:

Add isolation valves between mixer and manifold

 

Correct the orientation of the pump and mixer.

 

Form a primary loop between boiler flow and return.

 

Use a close coupled tee to UFH pump mixer 

 

Yup, agreed, but the isolations are probably moot as there is just so little system volume above the manifold rails to not have to worry about 'draining the whole system down'.

 

4 hours ago, Rubics said:

THanks Nick, 

 

I ran it for 10 hours and not much heat output (barely warms up the floor). The plumbers have agreed to make it right whilst keeping the manifold pump and blending valve. The flow rates need to be re-balanced. I can insist them to add the isolation valve as well.

 

Thanks

You shouldn't feel the floor, you should work out if the room is getting up to 21oC with relative ease (over x hrs) or not. How much screed is there and how much insulation is under it? 70oC to get to what you state is happening, is very worrying.

[Rubics]

On 13/11/2024 at 13:21, JohnMo said:

I would 

 

Add isolation valves between mixer and manifold

 

Correct the orientation of the pump and mixer.

 

Form a primary loop between boiler flow and return.

 

Use a close coupled tee to UFH pump mixer 

 

Thank you. They are coming back tomorrow to make it right. I will post an update soon

[Rubics]

On 13/11/2024 at 16:24, Nickfromwales said:

Yup, agreed, but the isolations are probably moot as there is just so little system volume above the manifold rails to not have to worry about 'draining the whole system down'.

 

You shouldn't feel the floor, you should work out if the room is getting up to 21oC with relative ease (over x hrs) or not. How much screed is there and how much insulation is under it? 70oC to get to what you state is happening, is very worrying.

We will find out tomorrow as they are coming back to address these concerns. Many thanks. I am also worried about a main system boiler they are working on. Shall I post it here for suggestions or create a new thread as its not to do with UFH? Thanks

[Rubics]

[Rubics]

[Rubics]

[Lofty718]

Is your house fully UFH? if so then that is highly inefficient and you could run the heating straight from the boiler with no inteference from pumps and mixer valves (which are crap old technology anyway)

 

This could of been a much cheaper install, by scrapping the mixer, pump and actuators and just getting a VRC720

[Rubics]

The main system boiler is not feeding any UFH. Its serving around 16 radiators and a new hot water cylinder. The small combi boiler is serving the new UFH section of the house. Thanks

[Lofty718]

That's insane, why do you have another boiler i'm sure your system boiler alone would of been more than capable of running all the rads and the UFH!

[Rubics]

Two main reasons they mentioned. 1) Keep the UFH pipes clean by not allowing radiators to mix with UFH 2) Backup boiler in case one fails. In my head I was hoping that one could do radiators + UFH but this was recommended as gold standard! What hurts is me having to rely on this forum and my network of friends to make things right even after paying the qualified plumbers to fit things properly. how would anyone know if the plumber has done things properly or not these days? End of the day things will work somehow and we trust it all done correctly but only experts could call out faulty installations. Thanks

[Lofty718]

I have an unvented cylinder and a mixture of radiators and UFH. Many people have this setup and it's no problem at all to have one boiler that does everything, these installers sound like total scam artists trying to fleece you and the work is substandard, you should get rid of them and do not pay a penny more. Being qualified means nothing nowadays unfortunately, but you are in the right place now to get sound advice on getting it done properly 

[ectoplasmosis]

As mentioned, having two boilers for your kind of heating system is madness. Ditch your 'installers'.

[Nickfromwales]

Yup, the second boiler is just madness. A flush, chemical treatment, and mag filter is all that's needed here. Jeeeeeeeeeeeesus.

 

Why have they used a plate heat exchanger if the Vaillant is only servicing rads?!