Underfloor heating...confused!

[Doobrey]

Hi guys,

Need some advice. The situation is as follows.

I have radiators upstairs in the house, controlled by their own control panel (allowing me to set the times that they come on). This works perfectly. If I override the setting, the boiler comes on and they fire up.

Downstairs I have underfloor heating. This "used" to come on when the thermostat indicated, you know, like 19 degrees, heat up. Downstairs also has a digital timer for controlling the hot water and underfloor heating.

The hot water works perfectly - so if I override it on the digital panel, the boiler kicks in straight away.

The issue I have is that the underfloor heating does not come on! It used too! I have set the digital timer to continuous, I have changed the thermostat (as it was suggested the old one could be faulty). When I set the thermostat to say 23 degrees or hotter, I hear the pump upstairs do something, but then the boiler does not start up.

I have a suspicion that it's down to a faulty motorised zone valve. But as I am not this way trained, I am unsure.

Some details :-

Thermostat is a DT90E
Motorised zone valves (3 of ) are V4043
Digital Timers are ST610)C
There is a Honeywell Wiring Centre involved too. I have uploaded 2 of the underfloor heating diagrams for help!

Basically the question is what could be wrong? Where do I start?


[ View media item 16945 View media item 16944 [/img]

 

[bellairaphon]

how long does the pump make a noise for? the valve crossing over will be giving a live to pump and boiler. when u select heating on your ufh what does the valve do can u hear it make a noise does it motor across?

nath

 

[bengasman]

No manifold, mixer, second pump?

 

[Doobrey]

So, when the radiators gp on the valve moves across...

When the under floor heating go on the valve does not move...

 

[Doobrey]

Ok guys,

Some more information....

I have closed off all of the valves except the "grey" one. Raised the thermostat to 23 degree and the boiler switches on and off at times...(I would have thought it would have stayed on until 23 degrees was reached?)

I then went to the airing cupboard and decided to see which syncho motors had gone across. Just the one that i had recently changed. I then decided to try something, and moved the one across which is coming straight out of the immersion tank (is that the right work - tank in the airing cupboard?!?). The boiler came on and stayed on....

Do I need to replaced the Syncho motor next to the immersion tank? How can I tell? What makes that Syncho motor move across?

Doobs

 

[Doobrey]

Ok another update.....

I have taken the left hand valve off of the system, after closing both red taps and have then opened up the bottom tap. Water seems to flow, although slowly through the system.

I compared this to a known working zone, and the water flow appeared to be about the same.

Untitled

• Doobrey
• 20 Nov 2009
• 5

 

[jackthom]

Does that mean the water is flowing through both upper and lower grey valves or just one of them? Not sure from your description.

 

[Doobrey]

Ok final check...

So, thermoostat on to 23 degrees!... Check
Closed all valves except Grey pipe (living room)... Check
Synchro motor moves across... Check
Timer set to continuous... Check
Boiler starts.... Check

Hot water flows through the bottom manifold and it going through the grey living room pipe.

The return pipe gets warm, but not as hot. I suspect this might be normal, as the living room loop is bigger than the others. However, when I open up the kitchen loop (next door) the return pipe is almost as hot as the starting pipe.

My thoughts are that I should really flush the living room pipe through, but I really need some advice guys.

Doobs

 

[Garfeild]

Noticed you've got 2 threads going on this subject,can you stick to one as we get confused too!

 

[njk]

Hi Doobs,

To get any air out of the ufh system you should close the two gate valves (red handle), connect a pipe from your main (outside tap) to the 3/4" connection on the left side of the lower manifold. On the left side of higher manifold, connect a garden hose (again a 3/4" connection) and bring the garden hose outside and place it in a bucket. (you can also use a kitchen sink it that is easier).

Then you close all the loops, top and bottom manifold and open the loop you want to clear the air from. On the left of the manifold there are two valves you open to get the water through. The bucket will fill quite quickly, but keep the hose in the water in the bucket and you will see the air bubbles, keep flushing until you haven't seen any bubbles for at least 1 minute, then the loop should be clear of air.

On another note, as bengsaman said, you don't seem to have a mixing valve or a secondary pump. Also, you don't have any actuators at all.
The mixing valve should mix the water before it goes in your floor, if you have concrete floors the water should only be apr. 45 C maximum.

And lastly, it sounds like you system has not been balanced.
a 50m loop will get warmer much quicker than a 100m loop, so all shorter loops have to have slower flowrates than the longer ones, so the whole floor gets warm evenly.

Lolli