UFH help

[Stevenwithav]

I have change the settings, I changed them to suit our need as a family, it works and heats up but  say in the afternoon when it gets cold in the house and I turn up the UFH thermostat, the pump starts up and it circulates cold/luke warm water, so even though the settings have changed it never circulated hot water when the rads/towel rails aren’t on

[Nickfromwales]

6 hours ago, Stevenwithav said:

I turn up the UFH thermostat, the pump starts up and it circulates cold/luke warm water

Is this the case if the boiler is already lit and burning to heat any rads? Eg the already heated (hot) water in the primary pipework isn't getting to the mixing valve and manifold loops?

[ProDave]

12 minutes ago, Nickfromwales said:

Is this the case if the boiler is already lit and burning to heat any rads? Eg the already heated (hot) water in the primary pipework isn't getting to the mixing valve and manifold loops?

I think the point and what started the thread is the radiators are not on and the UFH on it's own was not triggering the boiler to fire.  Not surprising now we have found that disconnected grey wire.  

[Nickfromwales]

2 minutes ago, ProDave said:

I think the point and what started the thread is the radiators are not on and the UFH on it's own was not triggering the boiler to fire.  Not surprising now we have found that disconnected grey wire.  

Yes, sorry, just been a long day and clarifying.

A plumber setting the towel rads to run with UFH simultaneously isn't that bad an idea. I do recommend that if there's a small UFH system or just one room of UFH with a couple of loops. 

 

Not connecting the grey wire is just bloody stupid though!

[Stevenwithav]

NICKFROMWALES: Yes if the boiler is already on for the rads or the towel rails and I turn up the UFH thermostat then the hot water will circulate around the UFH, that’s the only way I have been using it, 

but the problem with that is the rads and towel rails are on timers to come on and off, so if it’s particularly cold and I want to warm the downstairs it just circulates cold water around! So I really need to be able to heat the UFH independently, 

 

PRODAVE: if the gray wire is linked to the 2-port valves and I turn up the UFH thermostat should that call for heat?

 

p.s I can’t figure out how to reply directly to your message

[Nickfromwales]

13 minutes ago, Stevenwithav said:

p.s I can’t figure out how to reply directly to your message

Just either quote selection, or for specific parts of a post, just highlight a sentence etc and the quote box will pop up, then click on it.

 

If you make a hash of it before posting, don't worry, just refresh the page and click back on the comment box, your hash will reappear, then you just select 'clear editor' and you can have another go.

 

Also for tagging members, just type the @ symbol followed by the first couple of characters of the username and there will be a drop down list, choose the one you want and click on it  

[Nickfromwales]

[ProDave]

58 minutes ago, Stevenwithav said:

PRODAVE: if the gray wire is linked to the 2-port valves and I turn up the UFH thermostat should that call for heat?

Yes that is what we expect to happen.

[Stevenwithav]

10 hours ago, Nickfromwales said:

Just either quote selection, or for specific parts of a post, just highlight a sentence etc and the quote box will pop up, then click on it.

 

If you make a hash of it before posting, don't worry, just refresh the page and click back on the comment box, your hash will reappear, then you just select 'clear editor' and you can have another go.

 

Also for tagging members, just type the @ symbol followed by the first couple of characters of the username and there will be a drop down list, choose the one you want and click on it  

Got it , thanks

[Stevenwithav]

9 hours ago, ProDave said:

Yes that is what we expect to happen.

And if that works do you think I could just add a separate 2-port valve on the UFH pipe going to the pump and wire that into the same connectors in the junction box to be able to control only the UFH? 

[ProDave]

1 hour ago, Stevenwithav said:

And if that works do you think I could just add a separate 2-port valve on the UFH pipe going to the pump and wire that into the same connectors in the junction box to be able to control only the UFH? 

I would try it without first.  Water won't flow through the UFH pipes if the UFH is not demanding any heat so no harm done.

[Stevenwithav]

On 09/02/2025 at 22:05, ProDave said:

[Stevenwithav]

@ProDaveI have attached the grey to the greys from the 2-port valves, I turned up the UFH thermostat and the pump kicked in and the boiler started up, so that’s working as I wanted, thank a million, 

but is there any issue that can come from it being like this, like one of the other fellas on this thread mentioned something about “short cycling” and it using a sh*t load of gas! Or is this set up how it should have been? 
(the grey wires went into this terminal block with the arrow)

[ProDave]

Glad it is working.

 

See how it goes in practice.  The short cycling issue might arise if say just one of the UFH loops was calling for heat especially if it was a small room.  That would not be much load on the boiler so you might hear it fire up just for a short time then stop again.

 

There are options if that causes a problem and one is to make all the UFH work as one zone, all on, or all off.

[JohnMo]

You will soon find out if it's ok. Would monitor you gas consumption over the next couple of weeks to see what happens. Then there will not be a surprise bill in a month's time if it's running rubbish.

[Stevenwithav]

@ProDavealso the temperature on the pump shows 65 degrees, it used to be about 50, is that normal

[JohnMo]

That temperature is way to high, turn you mixer flow temp down.

[ProDave]

 

The knob on the bottom of this will adjust the temperature.  Turn it down until the flow temperature gauge reads about 40.  You will have to adjust it then wait a while for the water in the system to cool down, then adjust again.

[Stevenwithav]

I’ve adjusted it down to 45 but any lower and it makes a loud ringing sound

[Nickfromwales]

1 hour ago, Stevenwithav said:

I’ve adjusted it down to 45 but any lower and it makes a loud ringing sound

It’ll do that until the system acclimatises and ‘cools down’, the question will be is how low can you set it to still maintain room temps / not take an age to heat back up from start. Leave it set lower and allow it some time to stop it complaining. 

[Stevenwithav]

Good morning all, an update on this issue, it’s now working as I wanted so thank you all for your input, the only issue I now have is when the pump comes on it has that ringing sound (can be heard throughout the downstairs and the bedroom above) I’ve tried adjusting the flow but the only thing that stops it is if I turn the mixer up but that puts the temperature through the manifold to high, any thought on this, cheers 

[JohnMo]

 

1 minute ago, Stevenwithav said:

any thought on this

Back to my original post? Flow needed for UFH on its own is small with a mixer. In flow terms your trying to push an elephant through your front door.

 

You are likely going to need to flow radiators and UFH at the same time. Or put your UFH on a secondary loop via a close coupled tee.

 

 

[Stevenwithav]

I have the radiators and the UFH set to come on in the mornings, so I had all 5 UFH zones on and 6 upstairs radiators come on, but thats when the ringing sound comes on 

[Stevenwithav]

Also I’ve checked the daily gas usage and it hasn’t changed from prior to this fix

[JohnMo]

1 hour ago, Stevenwithav said:

but thats when the ringing sound comes on

But is that because closed the UFH mixer right down to get away from 70 Deg flow temperature?