Advice needed. Issues with underfloor heating and hot water system for new build

[chris watkins]

My two pennies worth - As I understand it (& I have only skimmed read through post) hot water on it's own works & heating on it's own works ? So why not just set time clock to allow heating of cylinder before U/F heating is allowed to come on if timed or if on continuously then at times least likely to effect heating?? If this works then fine for the moment (could also think about installing diverter valve with HW priority)
The long & short is that boiler / pipework can't supply both simultaneously as installed so if you want / need a long term solution then it's going to require what the boys are suggesting.
P.S. What is the third timed zone on the Horstmann, towel rails ?

 

[diamondgas]

If there is an undersizing issue then you could maybe consider installing a separate boiler for the water alone? That may work out cheaper than rejigging, IF that's required? I'd still like to know what circulating temps you're getting with different scenarios. I've seen extremely large houses run on a 15mm one-pipe system work no problem ... but heyho! Not at the property so I'm not experiencing what the installer is! You could even potentially have an issue with the new appliance that's starving the installation of heat? I could throw a few more 'possibilities' in the pot, none would be of benefit to be honest! Striping it back to basics you need to know (A) that there's enough heat being produced; you can then look at circulation and balance if you have (A)... If you haven't got (A) then there's a possibility that when the heating comes on it 'sucks' the heat out of the cylinder, the coil in effect works in reverse as colder primaries draw heat FROM the cylinder resulting in colder hot water .... Monitoring primary F&R temperatures can tell you a great deal about how well the demands are being met ....IMHO

 

[Centralheatking]

Looks to me like Diamond gas has got it right - its a nice set up but underpowered
just go get another boiler and hook it in as suggested CHK

Its been a great post 10 pages and 35 likes and we all have
learned from it thank you CHK

 

[Gray0689]

If there is an undersizing issue then you could maybe consider installing a separate boiler for the water alone? That may work out cheaper than rejigging, IF that's required? I'd still like to know what circulating temps you're getting with different scenarios. I've seen extremely large houses run on a 15mm one-pipe system work no problem ... but heyho! Not at the property so I'm not experiencing what the installer is! You could even potentially have an issue with the new appliance that's starving the installation of heat? I could throw a few more 'possibilities' in the pot, none would be of benefit to be honest! Striping it back to basics you need to know (A) that there's enough heat being produced; you can then look at circulation and balance if you have (A)... If you haven't got (A) then there's a possibility that when the heating comes on it 'sucks' the heat out of the cylinder, the coil in effect works in reverse as colder primaries draw heat FROM the cylinder resulting in colder hot water .... Monitoring primary F&R temperatures can tell you a great deal about how well the demands are being met ....IMHO

May be a cheaper way to

 

[Centralheatking]

Just a quick question Grey 0689 but How do you cope sharing the same Island with Jon Cropp ?

he is my friend but I feel safe knowing its ferry ride away CHK

Mind you we are visting Feb as we have a contract 3 vans and
we are staying at Croppies !

May be a cheaper way to

 

[Gray0689]

Just a quick question Grey 0689 How do cope sharing the same Island with Jon Cropp ?

he is my friend but I feel safe knowing its ferry ride away CHK

Where both too blow ins
And he a southern softy too lol

 

[Gray0689]

Just a quick question Grey 0689 but How do you cope sharing the same Island with Jon Cropp ?

he is my friend but I feel safe knowing its ferry ride away CHK

Mind you we are visting Feb as we have a contract 3 vans and
we are staying at Croppies !

Lol croppie take you to a few good spots I'm sure lmao

 

[diamondgas]

Looks to me like Diamond gas has got it right - its a nice set up but underpowered
just go get another boiler and hook it in as suggested CHK

Its been a great post 10 pages and 35 likes and we all have
learned from it thank you CHK

To be honest CHK I've no idea whether it's undersized or not ... reading others more up on sizing seems to indicate an issue. The only way I see knowing for sure would be to monitor F&R temps. If a boiler is undersized it will be working flat out but flow temps will never get close to max for ages, if at all! OP did mention 71degC .. Not that hot in my experience.

If I was to offer a workaround for now I'd suggest a pipe stat on the primary flow linked in series to the hot water timing and zone valve allowing water to be heated only if the primary flow temp was above, say, 60 DegC?

 

[Howsie]

Chuck an ATAG or Viessmann in.

 

[Carrera]

Hi, all and thanks for the feedback and suggestions to date, thought I'd give an update, I'm learning too so bare with me, although I like technical things. Also I am glad that people are finding it interesting. I will not stop posting until is is resolved, in the hope someone learns something, mainly me at this rate.


With your help the plumber has started to look at the flow issues
Where are we
In order to leave something working for xmas the magna was removed and replaced with now two small pumps, one replacing the magna and one on the flow return just under the bolier, system flushed through removing air
told not to use for than 3 manifolds at a time, and heat water separately.
they will be back early in the new year, accompanied by a consultant/design engineer.


has the system ever worked?
originally a year ago, the whole heating was running at 22c to dry the house, and it kept it there, however I did not monitor flows at that time.
also only used parts of it since some of the house is not complete
hot water with heating, found issue when we moved in after water was only ever Luke warm
towel rails I have not really used it can draw into mix, but at the moment leave to one side
bolier sizing was done by the energy consultant based on heat loss, trying to get an e copy of the numbers for those who are interested


How's it working
hot water only, starts off heating fine, but as cylinder gets warmer boiler starts to cycle every 2 mins for quite some time until the cylinder stat eventually switches everything off.
3 manifolds I tested yesterday work fine, flow rate at ports varying between 1.5 to 2 l/pm, with 40 to 42c flow and 30 to 32c return at each manifold. Got temp in heated areas to 21 to 22 within a couple of hours and switched off at around 2pm, outside temp 6c, never came on again for the rest of day, morning temp in those heated areas ranges between 19 to 21 depending on room as some have lots of glass, overnight temp 0c, only just switched on the now to top up.


boiler working very gently, output temp of 71c


manifolds. M1, 9 ports, m2 9 ports, m3 10 ports, m4 8 ports, m5 10 ports, m6 5 ports
flows up to heating are, first one is m2 and m3, second one is m1, m4 and m10
m6 is the basement and flows off the piping to the cylinder


Time to do some scenario testing if I can, happy to take suggestions and I can post results.


boiler temperature can be turned up, it on setting 5 and a bit at the moment give 71c?


flow and return temps under what scenarios? Easiest way to measure the temp? I have an ir thermometer, but how to get it to work on copper?if reliable at all?


manifold combinations, can switch all on to see what happens or one at a time?


best to have some results on the table before the guys come back to help get to a solution, whether it be a complete rehash, or mods to existing


merry xmas by the way and once again thanks.