Splitting UFH from main boiler circuit

[whoschuffed]

In the house we have just bought we have a Baxi combi boiler which powers UFH downstairs and radiators upstairs.

One thing i'm not hugely happy with is how it is all on the same "circuit" (thats probably not the right name for it). It's all controlled from a Nest thermostat in the hall but it's a bit annoying how we can't have just the UFH on downstairs or just have the rads on upstairs (if we have the log burner on downstairs for example).

It's a wet UFH system and the manifold for that is under the stairs with our boiler upstairs on the landing. Is it usual for it to be set up in this way and is there any way to change how the heating loops are set up so that we can independently control the upstairs and downstairs heating? Or is it a case of ripping out a lot pipework and starting again?

 

[Rodders53]

New build? Or older property?

We need much more info on the controls and installation.
Pictures of the UFH manifold, and all / any motorised valves around the boiler and any hot water tank, plus any other thermostats you can find would be useful.

Downstairs UFH loops should have individual room thermostats and 'actuators' to open the water circulation when required to each room's loop(s). Thus when the wood burner makes rooms hot enough those loops should switch themselves off... leaving the upstairs to look after itself.

Nowadays building regs require two zoned heating areas - controlled by stats and motorised valve - for UP and DOWN. Older properties would not, though - but most will predate wet UFH installs?

It should be simple enough to add such zoning valves if required though; albeit somewhat disruptive.

Most UFH systems have a dedicated circulating pump for the loops (separate from the main boiler pump) and generate a 'CH demand' from a wiring centre which could be isolated with a switch to manually switch off downstairs UFH as a 'bodge', perhaps?

You need to hunt out any manuals or guides supplied with the CH system - something sorely lacking in most installations.

 

[Mr Chibs]

My system has 2 x zone valves, one for the rads, one for the UFH (single room) both of these can be controlled independently.

 

[whoschuffed]

My system has 2 x zone valves, one for the rads, one for the UFH (single room) both of these can be controlled independently.

To the best of my know ledge mine does not.

New build? Or older property?

We need much more info on the controls and installation.
Pictures of the UFH manifold, and all / any motorised valves around the boiler and any hot water tank, plus any other thermostats you can find would be useful.

Downstairs UFH loops should have individual room thermostats and 'actuators' to open the water circulation when required to each room's loop(s). Thus when the wood burner makes rooms hot enough those loops should switch themselves off... leaving the upstairs to look after itself.

Nowadays building regs require two zoned heating areas - controlled by stats and motorised valve - for UP and DOWN. Older properties would not, though - but most will predate wet UFH installs?

It should be simple enough to add such zoning valves if required though; albeit somewhat disruptive.

Most UFH systems have a dedicated circulating pump for the loops (separate from the main boiler pump) and generate a 'CH demand' from a wiring centre which could be isolated with a switch to manually switch off downstairs UFH as a 'bodge', perhaps?

You need to hunt out any manuals or guides supplied with the CH system - something sorely lacking in most installations.

Thanks for the thorough response.

The house is a 1970's semi so not a new build. The boiler is upstairs and is a 9 year old Baxi Ecotec 28, we don't have any hot water tanks or similar.

I would have assumed the UFH was on its own loop by default but there are no separate controls and all of the heating is controlled from the Nest thermostat in the hall, so when we turn the heating on via that the UFH heating fires up as do the rads (upstairs - no rads downstairs).

I'll try and pop some photos of the UFH manifold on here to see if anyone can help. You say it should be simple enough to add zoning, do you know what is required? If its a bigger job I may actually get a couple of people in to quote as all of the rads look to be older single panel radiators which don't kick out too much heat.

I also have no idea whether the hot water is set hot enough for the UFH and radiators.

 

[Mr Chibs]

Think my flow from the boiler is tee'd off with the zone valves onto each flow pipe, this allows the heating loops to be controlled separately via a pair of thermostats.

I'm wondering if you could have this type of set-up applied.

My heating water temp is set to 50ºc on the boiler, and there is a blending valve (UFH manifold) to take the temp down further to something like 45º for the UFH.

Hope this helps.

 

[Mister Banks]

Shouldn’t UFH be “on” constantly anyway otherwise it would take far to long to heat the rooms.

 

[whoschuffed]

I don't believe so, no. It's an on-demand heating system. If it was connected to a stove/rayburn or similar then possibly but im not sure if that is even a thing haha but a good idea if possible.

 

[Mister Banks]

I don't believe so, no. It's an on-demand heating system. If it was connected to a stove/rayburn or similar then possibly but im not sure if that is even a thing haha but a good idea if possible.

I believe you shouldn't let the temperature drop by more than 4c below your desired temperature which means the system is in effect "on" all the time.

 

[Mr Chibs]

Mister Banks is correct, I have a fallback temperature of 4°c less than normal... which I currently run at 18°. The floor comes and goes as it's wants, in November it was once a day (usually in the morning) now it's more often now it's colder.

 

[whoschuffed]

Well blimey, what do i know! Haha.

Does anyone know of a way in which I can increase the temp of my system?

There is a temp dial on the UFH manifold that is reading at 45c constantly and I feel like i've read they can go to around 50c in most cases.

Is it a case of increasing the temp on my boiler (that is currently set to 50c for the rads) or do I need to change something on the UFH manifold to modify the mix of hot/cold?

 

[whoschuffed]

https://imgur.com/a/6aGPchr

Would turning the dial with ESBE on be the way to control temp?

 

[Madrab]

Would turning the dial with ESBE on be the way to control temp?

That controls the flow temperature into the UFH loop(s) and depending on the floor covering, could be turned up.

Is you UFH in screed? If so then you need to keep it 'warm' all the time to ensure it is efficient at heating the spaces properly.

 

[whoschuffed]

I tweaked it very slightly and could see the temp going up and down slowly so will have a play about with it to get a degree or two higher.

The UFH to the best of my knowledge is in screed, yes.

 

[Rodders53]

That manifold has four loops (how many rooms) but NO thermal actuators to turn individual loops on/off. They'd be where the white caps are on the return side. UFH in screed needs many hours of running to get warm and input heat to the rooms... equally it takes just as long to cool down. Thus the loops are commonly controlled with room stats, which typically have 'normal' and 'set-back' temperature control to try to ensure the slab never cools too far.

Your manifold has one pocket thermometer on top of the flow elbow (which we can't see the dial of in the pic). The Esbe Blending valve 'nominal temp' setting should be close. My manifold is currently showing flow of 45 and return of a tad over 30 after it's been on for a couple of hours (after being off for 2.5 hours). 45 C is a common UFH set temp, but the "ideal" is as low as you can go but still have comfortable rooms... I've read sites that suggest a floor surface temp of 25C is too hot.

You could control the UFH by simply turning on/off the circulating pump according to your perceive 'need' of the downstairs rooms when using the wood burner as your main heat source. (It'd need a 'bodge' manual switch installing; and risk forgetting to switch it back on/off).

To do it properly would need two zone valves and the controls (e.g. two hives. one up one down. if that's a possible and you like hive). That'll allow the UFH downstairs to operate completely independently of the upstairs radiators. Each with their own time and temperature regimes, and ought to work with rather than fight the wood burner?

That's a job for the Spring or Summer I'd suggest rather than while the cold weather is upon us!

 

[whoschuffed]

The UFH services the downstairs which is an open plan hall, kitchen, living room, dining room and small downstairs bathroom.

I'm not sure of the sqm'age of the lot but its not a huge house by any stretch.

The thermometer on top of the elbow shows between 45-47c atm after my tinkering with the Esbe valve. I upped the boiler rad flow temp to 55c too as the rads didnt feel hot enough in the house (they probably need bleeding and balancing too to be fair).

Its a real toss up atm with the cost of energy. The system takes a good while to come up to temp after being off over night in the morning. so i'm wondering if it would be more economical to have it maintaining something like 16c over night as I only normally set it to 17c during the day and the house is mostly comfortable.

Can you do what your describe with the Zone valves and the Nest system? And yes agree, will just battle through the cold months as is and get things in line for next winter.