Boiler & heating zones- help needed please

[zoe61]

Hi so I have an issue with how my UFH and radiator zones are plumbed or maybe wired up- can someone please help advise on what I need to do? Currently my boiler just keeps turning on at random times and turning the radiators on evern though the Neo stat for radiators says it shouldnt be on. 

 

I had my UFH system designed by Wunda, I also told them that I wanted my radiators on a seperate thermostat so they sent me out the Neo Heatmiser kit with my order. My cousin then installed by boiler for me, at the time he said he thinks I need a seperate valve for the radiators because theres nothing to seperat it from the UFH zone, I've contacted him again and he has just told me I have the wrong system and can't help. 

 

I have attached pictures to show what the current system looks like. In my mind I have 3 zones on thermostats: 1 UFH for the lounge (wired), 1 UFH for the kitchen (wireless),  radiators (wireless). The lounge and the kitchen work fine, it seems that the kitchen and radiators are the one that are linked together.

 

Thank you.

[Nickfromwales]

Hi.

Looks like no 2-port zone valves have been employed to split the heating zones apart. Do you have any of these types of valves anywhere?

 

 

 

[Nickfromwales]

Do all the UFH loops get fed from that one manifold?

[dpmiller]

there's Tees with something running upstairs there.

[Nickfromwales]

Yup, likely the rads, possibly another UFH manifold. There should be at least one ZV at the boiler to allow just the UFH to run, bu this may have been deemed a correct installation to allow the rads to run simultaneously if to stave off short cycling when the UFH load is minimal. 

[zoe61]

@Nickfromwales- no i dont have anything like that image. All teh UFH is from that manifold.

 

Yes the pipes going upwards go the raditors. I wanted it so the radiators could run seperate. i.e.i like having the warm tiles in kitchen even during summer but dont want radiators on upstairs as its too warm

[Zed]

Hi, 

If the wireless thermostats used are neoairs, it might be worth double checking that the failsafe mode is switched off. If the rf connection between stat and receiver is lost, (can be quite often) it fires up the heating for a short period as a frost safety feature. This could explain the random bursts of heating even if the stat isn't calling for heat?

[Nickfromwales]

4 minutes ago, Zed said:

Hi, 

If the wireless thermostats used are neoairs, it might be worth double checking that the failsafe mode is switched off. If the rf connection between stat and receiver is lost, (can be quite often) it fires up the heating for a short period as a frost safety feature. This could explain the random bursts of heating even if the stat isn't calling for heat?

I think the rads are coming on as a byproduct of the UFH calling the heat, as there’s appears to be no way that this is set up to arrest the flow of heated water to them ( if there’s no ZV fitted ).

When rads are deselected, a ZV should shut to isolate the rads so the UFH is the only place heated water gets to.   
As I’ve said, this would promote short cycling so maybe this was set up ( albeit inadvertently ) to use the rads as a bypass when the UFH cannot dissipate the heat output of the boiler on its lowest output. 

[zoe61]

@Zed I've just checked and the failsafe mode was enabled. I've been struggling with internet connection the last couple of weeks and the problem only seems to have arisen then actually so hopefully that may fix the random kicking in of the boiler.

 

@Nickfromwales if I was to fit a 2 port zone valve to the radiator pipes would this then fix my issue and put the raditors on their own zone please? Or would it create more problems (i'm a bit concered about the short cycling comment and dissipating heat)?

[Nickfromwales]

You may be better off fitting smart TRV's to the rads and leaving one strategic radiator as bypass ( a towel warmer / bathroom rad possibly ). Short cycling wont kill the boiler, but it may reduce longevity. Which boiler do you have - make / model / kW? Maybe a good exercise would be to put the kitchen UFH on on its own and just sit at the boiler for a half hour or so to see just how many heat on / off cycles it does. Wait until the heating is up to temp before doing this check, as it'll be under duress whilst achieving the required heat output, which won't cause much short-cycling as that is heat thirsty, but then it'll need very little to keep it there once stabilised which is when short-cycling is likely to be at its worst.

Short-cycling is caused when the boiler produces more heat ( at its lowest output ) than the heat load can absorb and dissipate into the dwelling. This is worse with UFH as the thermostatic blending valve on the UFH manifold will also refuse any temps over the set value. Typically 30oC-34oC and the boiler heat dial would have to be set a lot higher a the rads would never get warm enough if the boiler was set to match the UFH only. This is why people sometimes end up fitting small buffer tanks between boilers and UFH, particularly if rads are involved ( eg two different types of emitters each requiring two different temps, sometimes at the same time, and from the same heat source ).  

[zoe61]

Thank you that makes sense! Ideal Vogue max combi 40