Underfloor Heating And Combi Boiler System

[davenellie]

Hi everyone please can someone help!

I have had an extesion built with underfloor heating (UFH) installed. As my gravity fed system wasn't up to the task I had a Combi system installed. In his wisdom the plumber removed the Hot water tank, and helpfully replaced it with a flow and return ready for the UFH isolated by the old three port mid position valve. I assume this would be classed as a Y plan allowing for UFH only, CH only or both!!!

The problems came when wireing the controls from the UFH and CH separatly to the 3 port valve. On the first attempt we had hot water going to the CH at the same time as the UFH even when the CH was set to off. (this is because i think the vale was in mid position)

On the second attempt the CH stays hot when UFH is on and calling by doesnt get any hot water so stays on (house boiling, extension cold!!!! (this is because the valve has motored to CH only but not returned when satisfied.

The builder has had a new controller fitted to the wocester bosh boiler for the extra tap!! and replaced the room stat for a stat/programmer.... but still failed to set it up right. Now he wants to blaim the plumber....

Question - is it possible to have this system working with the current Y plan valve or would we need to switch to an S plan system for simplicity? ( I assume this will need to re plumbed)

There are currently five cables entering the control box which I assume are 1x boiler control, 1x programmer, 1x room state. 1x UFH stat and another from the UFH possibly programmer??

There is of cause the 3 port valve cable.

I would post pic but im new to forum and dont know how??

Any help would be appreciated as im fed up of being taken for a ride having payed a lot of money for a lemon so far....

Dave

 

[steptoe]

2 x 2 port valves are better, but, there is absolutely no reason this will not work with a mid position valve,  you simply need it connected up properly, 

You will need 2 stats,  1 for ufh and 1 for ch 

 

[Andy™]

it can be done easily... output from CH of boiler into middle of 3 port valve. one side to UHF, other side to normal CH. 2 channel programmer used with 'hot water' side doing UHF, CH doing CH. no control for DHW other than the normal on/off switch on the boiler. fairly simple really.

looks like another example of plumber / electrician not knowing a thing about how heating systems work

 

[davenellie]

Yes, thanks for reply.

The UFH is fully installed with progammer and stat in extesion. the intention was to engnor UFH programmer and set it to on constant and just turn stat up/down as neccessary. The house would then operate as normal with programmer!!

Dave

 

[steptoe]

Yep, just to add about the 2channel programmer, it's unlikely your current progstat has 2 channels, just get a normal 2 channel programmer, (grasslin qe2 for example) and 2 stats 

 

[davenellie]

I had the boiler replaced by a plumber as recommended by builder who is to install UFH. pumber fitted boiler fine however my builder and electrician have struggled ever since to get the two systems to work together.

 

[davenellie]

how do I add pics on here?

 

[Andy™]

you cant yet

 

[davenellie]

I know that I've tried, but when, how, why???

 

[Andy™]

you need at least 10 posts. its to stop spammers etc joining and posting crap. hang around a bit and an admin will chage your account for you

 

[davenellie]

Thanks Andy

 

[NozSpark]

This should work,,,, unless they've installed a priority type 3 port valve instead of a mid position one.

I would however say that a S plan is far superior

 

[Sharpend]

Min of 10 posts Dave, for anti spamming purposes, but a friendly mid/admin may be along who can assist.

At reason why forum clock hasn't changed?

 

[davenellie]

Only opted for a Y plan because the existing valve wasnt that old. Plumber just used what was available and I didnt know any better. By the time im finished I'll be an expert, (and the wife, shes not too happy its taken this long to sort out !!)

Dave

 

[Sharpend]

Dave what's your location, someone may be local to you?

 

[davenellie]

Thanks for the kind offer, but Ive paid someone a lot of money and there going to fix it. Im just doing my research so I can get them to do what ive paid for. failing that I'll be in the market for a good engineer soon....

 

[Steve3948]

Only ever seen undefloor operated through 2 Port Valve, how is the ufh manifold controlled, as the water in the ufh is a much lower temperature.

 

[Andy™]

At reason why forum clock hasn't changed?

its just you. correct time here

 

[davenellie]

Im lead to believe the UFH cycles water with it own pump. a thermostate set to max 45 deg allows CH water to enter the cycle if needed, so UFH never exceeds 45 deg and CH is only called for if room temp drops. I think there is a pressure relief between the flow and return should the boiler be pumping and no flow required???

 

[davenellie]

Can I post Pics yet Mr Admin man.....?