UFH has its own pump that keeps running round the clock!

[k.udhay]

Hi, I moved to a house recently where it is installed with city heating system. As I understand from past records, the original house had only radiators that were fed by a thermostat-controlled heat exhanger with a pump to circulate hot water. One of the previous tenants installed under-floor heating which has its own pump. However this has no thermostat on its own (or at least I couldn't see one). Also this doesn't get water directly from the city heating water inlet. Instead it gets hot water only from the original heat exchanger which already supplies to radiators. Therefore I have two following problems:

1. The floor heating pump is only manually controlled - "I" have to turn it on or off. If I forget to turn off, it runs round the clock.
2. Even if I leave the floor heating pump on for long, it is also possible that it has been only circulating cold water under the floor, if the thermostat the controls heat exchanger was set at temperature less than room temperature.

Here are my questions:
1. Is it a usual (or one of the usual) way(s) how an under floor heating system is added to existing radiator heating system?
2. Is it okay, to leave the under floor heating pump to stay on throughout winter? I can certainly understand it is a continuous wear to the pump. But may be it is possible that these pumps are designed considering such usage?
3. Do I need to check anything closer because my description of the heating system seems illogical to you? May be the floor heating pump is also controlled by the thermostat but I am not checking that correctly?
4. Assuming the problem I described so far is correct, do you think there are some easy-yet-clean fixes I can try?

TIA

 

[John.g]

Does it look anything like this where the pump mixes hot water from the boiler with UFH return water to give cooler (35/45C) water to the UFH.?.

 

[k.udhay]

Does it look anything like this where the pump mixes hot water from the boiler with UFH return water to give cooler (35/45C) water to the UFH.?.

View attachment 66055

Hi,

Yes more like the picture you shared. Attaching pictures of my house setup...

 

[John.g]

Its possibly teed off from the rads HIU unit which is probably correct as I don't think one is/should be allowed to take it from the city heating water supply/return (primary water side). You should have a form of S plan where you can run Rads only or the UFH only (and both) but the UFH only would normally require the heat exchanger circ pump to run as well to supply the hot water to the UFH manifold. Can you pose a few photos of the HIU set up including circ pump.

 

[k.udhay]

Its possibly teed off from the rads HIU unit which is probably correct as I don't think one is/should be allowed to take it from the city heating water supply/return (primary water side). You should have a form of S plan where you can run Rads only or the UFH only (and both) but the UFH only would normally require the heat exchanger circ pump to run as well to supply the hot water to the UFH manifold. Can you pose a few photos of the HIU set up including circ pump.

Will send some pics in the evening once I reach home. Thanks for giving some important key words so far, I was able to read information on S plan.

 

[SimonG]

What country are you in??

 

[k.udhay]

Its possibly teed off from the rads HIU unit which is probably correct as I don't think one is/should be allowed to take it from the city heating water supply/return (primary water side). You should have a form of S plan where you can run Rads only or the UFH only (and both) but the UFH only would normally require the heat exchanger circ pump to run as well to supply the hot water to the UFH manifold. Can you pose a few photos of the HIU set up including circ pump.

 

[k.udhay]

What country are you in??

The Netherlands

 

[John.g]

Where is the UFH piped in?. there seems to be 2X honeywell motorized valves, is the CH piped to one of these and the UFH through the other?, also see if the pump is feeding both of these.

 

[k.udhay]

So, the heat exchanger unit is on one side of the wall. From there under the ground few pipes go to the other side of wall under the stairs (set of pics. I sent at first). The challenge for me is to know what pipes are for UFH and what for radiators. I will try to find them again today.

 

[John.g]

When you switch in/on the CH you should see one of those motorized valves opening, I don't know if the other is for a different zone (or HW) but you should be able to figure out which one is also supplying the UFH manifold.

 

[k.udhay]

When you switch in/on the CH you should see one of those motorized valves opening, I don't know if the other is for a different zone (or HW) but you should be able to figure out which one is also supplying the UFH manifold.

Does it actually matter? Because from the CH I see only one hot water output which goes underground and connects to the distributor on the other side of the wall.

 

[k.udhay]

@John.g - A quick update. I called the floor heating device company (Therminon) this morning. According to them, the pump is designed to always be running. Basically I should let it run through out winter.

Is this some type of design you have come across?

 

[John.g]

It would be normal enough to run UFH 24/7 throughout the winter as long as its supplying some heat but your system is very basic in that the UFH pump is just started/stopped manually so if the CH (rads) is not running then there is no supply of HW to that UFH pump which distributes it around the UFH . At the very least, that pump should be auto start/stopped with the H/exchanger circ pump from the CH timer or preferably a separate zone (motorized) valve via a (UFH) room stat which will then start/stop both pumps irrespective of what the rads circuit is on or off, that is why I asked what those two motorized valves are doing?.

 

[k.udhay]

May be the second motorize valve is for other hot water supplies like shower and sink?

It would be normal enough to run UFH 24/7 throughout the winter as long as its supplying some heat but your system is very basic in that the UFH pump is just started/stopped manually so if the CH (rads) is not running then there is no supply of HW to that UFH pump which distributes it around the UFH . At the very least, that pump should be auto start/stopped with the H/exchanger circ pump from the CH timer or preferably a separate zone (motorized) valve via a (UFH) room stat which will then start/stop both pumps irrespective of what the rads circuit is on or off, that is why I asked what those two motorized valves are doing?.

May be the other motorized valve is to supply hot water for shower or sink?

 

[John.g]

Have you a close up view of the writing on the front of this?.

 

[k.udhay]

Have you a close up view of the writing on the front of this?.

I will take it this evening

 

[k.udhay]

I will take it this evening

Hi John. Pictures attached

Have you a close up view of the writing on the front of this?.

 

[k.udhay]

The text is in Dutch. I don't know if that can still help us!

 

[John.g]

Here is the translation, not much use.

So do you just turn up the roomstat to start the CH and does this then start the circ pump in the photo.
and ditto for the HW, how do you get it, do you just open a hot tap (does it also start that circ pump) and when both are off is this circ pump off as well?.

 

[k.udhay]

Here is the translation, not much use.

So do you just turn up the roomstat to start the CH and does this then start the circ pump in the photo.
and ditto for the HW, how do you get it, do you just open a hot tap (does it also start that circ pump) and when both are off is this circ pump off as well?.

View attachment 66369

 

[k.udhay]

The pump turns on only when radiator valve is actuated via temperature controller.

When I open sink or shower the marked valve is actuated (may be by pressure difference?)

 

[John.g]

If you want the UFH to actuate this valve (and pump) independently of the radiators then you need another zone valve teed in before the radiator one and actuated by a UFH timer and roomstat like a S plan so will probably need professional help to achieve this, a cruder/simpler system would be to supply the UFH manifold pump from the radiators zone valve but you then don't have independent control of the UFH system.

 

[k.udhay]

If you want the UFH to actuate this valve (and pump) independently of the radiators then you need another zone valve teed in before the radiator one and actuated by a UFH timer and roomstat like a S plan so will probably need professional help to achieve this, a cruder/simpler system would be to supply the UFH manifold pump from the radiators zone valve but you then don't have independent control of the UFH system.

Hi John,

Thanks a ton for providing so much help. The main two reasons I wrote this post here were to know:
1. Can the UFH pump run through out the winter?
2. If not, is it practical for me to make it automatically controlled by the central heating unit.

You already answered (1) and now also (2). I believe I have understood what I wanted to.