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UfH controls methodology help


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Hi everyone, hope your all well🫡

can someone explain UfH controls to me please? I can’t wrap my head around it!

 

I’ve watched loads of videos on valves and relays that switch the boiler etc but I opted for a funny boiler which has made things worse?

 

I currently have an Ariston Clas one, 7 radiators and a Cube thermostat which is ariston’s fancy weather comp app control stat

 

All works great and does all the modulating jazz!

 

anyways, I want to convert one room to UfH downstairs, but I can’t get my head around how it operates via the boiler 

 

so in my head I’m thinking I keep my thermostat that turns the radiators on, and then I install an identical stat in the UfH room and that turns the floor on and off , I come home from work and say “ok google turn heating on”

both stats call for 20 degree heat and call the boiler , radiators get hot and turn off, under floor is still warming up so stays on a bit longer , all the zone valves do their thing and everything is rosy. 

 

but ariston uses a “bus” terminal for their fancy stats so you can’t really connect anything to it switch wise or relay wise, the boiler does have a normal volt free ta1 stat terminal and a ta2 floor stat terminal if I wanted to use normal stats but ideally I’d like to keep the ariston control because the app is pretty good, apparently ariston sell a multizone unit that can connect zone valves via their bus system but they are not much help on the phone

 

so then to make things even more complicated …..

 

I’ve seen videos of manifolds with blending valve and zone valves that everyone seems to use but I also saw a video where you do away with zone valves and use an ESBE actuator to do the blending 

 

this seems to be the best way but I can’t find any info for it

 

how do I find out about any of this land who do I ask?

 

cheers

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1 hour ago, SimonD said:

There will be quite a lot of input on this coming shortly, but first question is how big is the single room where you want ufh? Second question is how big is your boiler?

Room is 12m2, boiler is 24kw I think?

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To add UFH your floor insulation needs to be very good, most retrofit are not.  Also control really depends on floor buildup and depth of screed.

 

What's the motivation for UFH?

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12 minutes ago, JohnMo said:

To add UFH your floor insulation needs to be very good, most retrofit are not.  Also control really depends on floor buildup and depth of screed.

 

What's the motivation for UFH?

I have a 700mm deep void under the floor, was thinking of tipping 600mm of the small size foamed glass into it, bringing it up to joist underside, then a plastic grid to tie heat loops too, then add sand and lime to a specific ratio for UfH . The walls will also be insulated with woodfibre, new windows and small insulation in the ceiling, room will also be air sealed as much as possible. Main motivation is to get rid of the nuclear sized radiator on the wall that kind of stops any furniture going anywhere, it’s not a massive room and space is a premium

 

with the controls I’m really just looking to keep the ariston app control by using their products but there’s nowhere to find out, manages to speak to some random ariston parts place and he said it can be done but depends on what UfH I go for and to get back to him when I have more details, but now I’ve seen that method of using an esbe actuator and think that may be a better way , I don’t know

 

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10 minutes ago, Deniance said:

tipping 600mm of the small size foamed glass into

Ok, so you two ways to go with UFH attached to radiator system. Slow and steady via a mechanical or electronic mixer. I would go towards an Ivor mixer, they have plenty of adjustments to get things right. Then run at a slow steady rate. UFH when run long and slow can be self modulating.  An electronic mixer can be good and expensive, in most cases not really worth the expense. I am saying that as a person that owns one.

 

Have a low hysterisis (0.1) thermostat (Computherm Q20RF for example) connected to the pump stop and start.

Edited by JohnMo
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Just now, JohnMo said:

Ok, so you two ways to go with UFH attached to radiator system. Slow and steady via a mechanical or electronic mixer. I would go towards an Ivor mixer, they have plenty of adjustments to get things right. Then run at a slow steady rate. UFH when run long and slow can be self modulating.  An electronic mixer can be good and expensive, in most cases not really worth the expense. I am saying that as a person that owns one.

Ah right , I don’t mind which way I do it, I’d like to get good quality kit and have spares available easily , that’s my only ask really, then I’ve just got to figure out how on earth you 2 zone an ariston , I’ve read the manuals for the boiler and you can set zone one as a high temp rad circuit and there’s a second set of stat terminals labelled floor and you can set that to zone 2 and a low temp, but I don’t think you can have two of the fancy stats connected to the boiler , I might just have to have the fancy stat allowing app control for the radiators and get a normal cheap stat on the floor o activate zone 2, I’ve emailed ariston help but they have not replied 🙁

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15 minutes ago, Deniance said:

normal cheap stat

Are rubbish with UFH as you get big under and over swings in temp. The one I mean mentioned is about £60.

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So just to get things straight in my head

 

if I make a radiator zone and UfH zone I will have 2 zones with 2 individual thermostats that can call for heat independently

i will need 2 zone valves to isolate each circuit, so if both stats call for heat both zone valves open, when rads stop calling for heat the zone valve closes allowing the boiler to continue and feed the still on call UfH stat , and vice versa

 

i will also need to get installed , a close coupled tee at the boiler incase both zone valves were to be closed for some reason the boiler and it’s pump over run would no circuit to pump to and the boiler would shut off and go into fault, the close coupled tees allow enough of a circuit to stop it happening?

 

then the manifold has a blending valve that cools the water to low temp for the heating loops under the floor 

 

so if radiators and floor have open zone valves the boiler will produce high heat for radiators and the blending valve will cool it to protect the floor 

 

my boiler allows 2 zones and I think it can be set as zone 1 high heat and zone 2 low heat, so if zone 1 rads call for heat it can output high and the blending valve protects the floor , and if zone 2 floor calls for heat and the radiators do not then it can produce low heat and go straight through the blending valve anyways?

 

does that sound about right?

I’ll have to contact the plumber who I’m hoping will know all this but you can’t be too careful these days with trades! Just want to get an understanding in my head of what needs to happen that’s half the battle

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Also, do I use online UfH companies to design a drawing and supply the materials or will they just oversell stuff to me, with small diameter pipes and stuff that’s not needed? Or should I let the plumber decide on what to use?

 

 

 

 

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21 minutes ago, Deniance said:

close coupled tee at the boiler incase both zone valves

A close coupled tee can be anywhere in a circuit, but you just need to ensure you have flow to the CCT and back to the boiler.

 

I operate two zone one is the house UFH and the other is a summerhouse with fan coil. Both have a thermostat and can call for heat but both have to no longer require heat to shut off the heat pump. I run without any zone valves. If the summer house needs heat the floor of the house is also heated (acting as a buffer). In the last couple of months the house hasn't had to call for heat, as it's always hot enough just because the summer house is calling for heat more often than the house. Energy consumption isn't affected much in fact it's quite good.

 

My buffer, electronic mixer are being removed soon. So it will be ASHP, fan coil and UFH all driven from ASHP pump, two thermostats, either can call for heat, both off to stop heat.

 

So to simplify your system.

 

You run WC, is there any real need for zone valves at all, what do they do (DHW and heating)? Just run long and slow as WC is intended?

Your UFH will just need a mixer/pump to drop flow temp down to a suitable level. Leave it to run all the time. Apply KISS to your thinking go back to what you need as a minimum, remove the complication.

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I’m not sure what wc and kiss means, I’m not clued up on plumbing terms, just need a bit of an idea what I’m gonna be asking the plumber for, I have a combi so it’s doing hot water straight from combi, radiators and UfH

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2 hours ago, Deniance said:

not sure what wc and kiss means,

As above, so you have zero need for any zones valves with a combi. Just run as a single zone.

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1 hour ago, JohnMo said:

As above, so you have zero need for any zones valves with a combi. Just run as a single zone.

This is where I’m going to get confused now 😂 everything I’ve read and seen is saying I need zone valves, the heating gets to temp and turns off so the zone valve closes because the boiler is still on and supplying the floor circuit which hasn’t got to temp and is still calling for heat, so without the zone valve the heating circuit will still have water pumped through it? 

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5 hours ago, Deniance said:

This is where I’m going to get confused now 😂 everything I’ve read and seen is saying I need zone valves, the heating gets to temp and turns off so the zone valve closes because the boiler is still on and supplying the floor circuit which hasn’t got to temp and is still calling for heat, so without the zone valve the heating circuit will still have water pumped through it? 

But you say at the start of the thread your thermostat makes the boiler run in weather compensation. The idea is with weather compensation is the heating system just gives enough heat to the house to maintain the house temperature. The boiler runs for very long periods. So in theory the zone valves should never close.

 

You are referring to a heating system that runs at very high temperature with on off controls. So in that case the boiler would fire for a short period, the thermostat says the room is hot enough, switch boiler off temperature in the rooms drops, boiler fired up, repeat.

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29 minutes ago, JohnMo said:

But you say at the start of the thread your thermostat makes the boiler run in weather compensation. The idea is with weather compensation is the heating system just gives enough heat to the house to maintain the house temperature. The boiler runs for very long periods. So in theory the zone valves should never close.

 

You are referring to a heating system that runs at very high temperature with on off controls. So in that case the boiler would fire for a short period, the thermostat says the room is hot enough, switch boiler off temperature in the rooms drops, boiler fired up, repeat.

I was told it has it, the weather symbol displays on the thermostat, and it gets it through the internet, and the boiler is on auto which is thermoregulation, the boiler fires and you can see a power bar next to the flame icon, then when it nears temperature it drips down to 1 bar, but it does turn off, when I set temp to 20 it will heat and modulate but when it’s at 20 the stat definitely turns the boiler off, I bought an outdoor sensor for it but the service guy said I don’t need it as it’s all done through the internet with the thermostat 

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