Underfloor heating flow direction incorrect?

[HighTower]

Hi All,

We're been living in a new build property for the past 2 years without any obvious heating issues. We've an underfloor heating system that's split across 4 rooms, and is driven by a Daikin ASHP.

I've occasionally had to take the actuators off in order to release stuck pins after periods of minimal heating activity, but always noticed that the flow valves show 0 flow when the system is on or off. When pressing the zone pin down, the associated flow meter bounces and a knocking sound is heard through the pipe.

After watching a few videos online, I wondered if the system had been connected up around the wrong way, but couldn't find confirmation anywhere. When the system is running, if I manually depress one of the pins for about 30 seconds and take temperature readings off the pipes, I see 37 degrees beneath the actuator at the bottom of the manifold:

At the top, I see 26 degrees under the flow indicator for the same loop.

Am I correct in thinking the flow into the manifold is around the wrong way? If so, apart from not giving an accurate flow indication, does this cause any problems? The house is certainly warm enough through colder periods (22-23 degrees) but I wondered if the system would be as efficient as possible in this configuration?

Any advice gratefully appreciated.

Thanks,
Ben

 

[RoryD]

The flow is "set" via the flow adjusters - the red plastic units. You have to release the locking devices and rotate them to the desired/required flow rate. this should have been done at installation (clearly)! If the pins are sticking on the actuators apply a bit of washing up liquid and press a few times. you could use a dab of olive oil I suppose. With heat pumps it's advised to have a couple of actuators off. Check with Daikin.

 

[oz-plumber]

The flow meters should be on the flow.
You should be able to tell which is the flow from the from feeling the pipes to each side of the manifold.
The hotter pipe to the flow meters.

As with all the circuits with actuators, it would be worth removing a couple of actuators.
The actuators take up to 3 minutes to open and can cause detrimental effects on pumps and other parts of the system when the pump fires up and there is no flow.
You don't seem to have by-pass on the manifold.
I would remove a couple of the actuators in a common zone

 

[HighTower]

Thanks for the responses here, I'll follow the advice and remove one of the actuators.

I can also confirm that the bottom pipe on the left gets warmer first when the system is started from cold. 31.9 degrees C at the actuator side and only 22.6 at the flow valve side. This would seem to confirm the flow is in the wrong direction.

So the follow on question then remains in that does this cause any issues? Do the flow indicators and actuator pin valves have any issues with incorrect flow direction?

 

[Jaydeebee]

Thanks for the responses here, I'll follow the advice and remove one of the actuators.

I can also confirm that the bottom pipe on the left gets warmer first when the system is started from cold. 31.9 degrees C at the actuator side and only 22.6 at the flow valve side. This would seem to confirm the flow is in the wrong direction.

So the follow on question then remains in that does this cause any issues? Do the flow indicators and actuator pin valves have any issues with incorrect flow direction?


View attachment 73395



View attachment 73396

 

[Jaydeebee]

Hi, I have a Continal system installed (by them) for 14 years and mine seem the wrong way round (but it worked fine for years). I now have one manifold which intermittently doesn't get the room temp up. V hot supply pipe, warmish manifold pipe by flow guages and slightly less warm return pipe below (by the actuators). I'm starting to think it must be the mixing valve

 

[John.g]

Looks like you are feeding the manifolds directly from the boiler with no thermostatic mixing valve (boiler at UFH required temperature?).
You would think that the flow meters (if installed) might act somewhat like NR valves or at least impede the flow if flow is reversed, also how do they give a flow indication?.

 

[Jaydeebee]

Looks like you are feeding the manifolds directly from the boiler with no thermostatic mixing valve (boiler at UFH required temperature?).
You would think that the flow meters (if installed) might act somewhat like NR valves or at least impede the flow if flow is reversed, also how do they give a flow indication?.

 

[Jaydeebee]

I should have posted a better pic
Hit water comes in bottom left but I don't really understand how the pump and the mixer interact.
The top row of the manifold is deffo a little warmer than the bottom by the actuators which I understand control return valves. I just checked them and they all move up and down ok

 

[Jaydeebee]

I should have posted a better pic
Hit water comes in bottom left but I don't really understand how the pump and the mixer interact.
The top row of the manifold is deffo a little warmer than the bottom by the actuators which I understand control return valves. I just checked them and they all move up and down ok

Sorry, hot water comes in bottom right....

 

[John.g]

The mixing (TMV) arrangement is a bit strange from the usual combined pump/TMV set. Looks like the TMV is the red valve below the pump which is pumping upwards (arrow on pump body will confirm) so if the UFH (mixed) flow temperature increases, the TMV should throttle the boiler high temperature water and allow more "cold" water from the UFH return (bottom left) to flow so reducing the mixed temperature, or something like that, the pipe stat might just be set a few degrees than the maximum permissible UFH temperature and shuts the pump or system down as a safety feature.

 

[Jaydeebee]

The mixing (TMV) arrangement is a bit strange from the usual combined pump/TMV set. Looks like the TMV is the red valve below the pump which is pumping upwards (arrow on pump body will confirm) so if the UFH (mixed) flow temperature increases, the TMV should throttle the boiler high temperature water and allow more "cold" water from the UFH return (bottom left) to flow so reducing the mixed temperature, or something like that, the pipe stat might just be set a few degrees than the maximum permissible UFH temperature and shuts the pump or system down as a safety feature.

Thanks that would certainly make sense