HELP! UFH system causing boiler temp drop/excessive gas consumption

[kaye]

Hi Chris

Thanks for your reply. I can check this but essentially the more load taken from each of the 9 port manifolds the lower the temperature drop of the boiler.

I can’t see anything discharging from anywhere (and the boiler isn’t losing pressure so I guess that would drop if it was?).

Boiler temp set to 75 degrees.

I have attached a pic of the tanks/vessels already fitted but no red ones?

I understand from the plumber that Polypipe / the Polypipe dealer are aware of the boiler size/spec and have confirmed that it should be sufficient but that suggestion does put something else into the mix as a possible cause .

Also, the ufh is only turned on and off by the thermostats (and have them set to 18.5 off 20 on, the ‘on/20 degree time being between 3.pm and 8.pm. With the 9 port manifold in operation and the master bedroom suite calling for heat (and subsequently dropping boiler temp) it usually takes those entire 5 hours to lift the barn temperature 1.5 degrees to 20!

 

[chris watkins]

Grey vessel is the additional heating so good (most are red, sorry)
The set up sounds right at least with the controls etc.
It would seem that a site visit from an U/F expert may be required to get to the bottom of it.
Photos of each manifold might help.

 

[Old Account]

It will take approx 1 hour to raise the air temperature by 2deg C .

But that depends on room size doesn’t it?

 

[chris watkins]

But that depends on room size doesn’t it?

Given that the coil has been sized to suit the heat loss & floor coverings etc.

 

[Old Account]

View attachment 36197 View attachment 36198 Hi Chris

Thanks for your reply. I can check this but essentially the more load taken from each of the 9 port manifolds the lower the temperature drop of the boiler.

I can’t see anything discharging from anywhere (and the boiler isn’t losing pressure so I guess that would drop if it was?).

Boiler temp set to 75 degrees.

I have attached a pic of the tanks/vessels already fitted but no red ones?

I understand from the plumber that Polypipe / the Polypipe dealer are aware of the boiler size/spec and have confirmed that it should be sufficient but that suggestion does put something else into the mix as a possible cause .

Also, the ufh is only turned on and off by the thermostats (and have them set to 18.5 off 20 on, the ‘on/20 degree time being between 3.pm and 8.pm. With the 9 port manifold in operation and the master bedroom suite calling for heat (and subsequently dropping boiler temp) it usually takes those entire 5 hours to lift the barn temperature 1.5 degrees to 20!

Do you know how many Liters per minute each loop gets? You should see flow regulators at the Manifold are these set properly?

 

[kaye]

The size of the room is relevant in relation to temperature lift of course but it lifts the temp fine in the barn when there is no demand from the bedrooms run through the 9 port manifold as the boiler doesn’t drop temperature.

I have already asked for a second opinion from aanother ufh engineer (in addition to the original installer) which is when I had received my conflicting diagnosis (one said the LLH is required, other said route cause of issue is diameter of feed piles from boiler to manifold(s) due to the long runs of pipe - hence my post on here.

Either solution ref above is a fairly major job by the looks of things and I am concerned that one or the other proposed solution (or worse still both!) will not resolve the issue of the boiler temperature plummeting like a stone due to demand

 

[chris watkins]

For us (or them) to help we would need to know the loadings (heatloss) for the zones & the pipe sizes feeding each, it is easy to work out if the supply pipework can carry the required flow of water.
Are the manifolds Flow & Returns 22 or 15mm ?

 

[Chalked]

Gas consumption has more to do with the fabric of the building and heat loss. Not the system. But a badly set up and installed one will use a bit more.
You have a large building that will require a given amount of energy to heat it. If the building is well built, air tight and well insulated. It will be efficient. But if it’s draughty and poorly insulated, it will cost a lot more to heat to a given temp.

 

[king of pipes]

You need to get a engineer who understand how UFH works told you how I would do it my fellow members may have other ideas . Kop

 

[kaye]

Are there any ufh specialists on here that have had experience of larger properties/installs that are local and would be willing to commit to a diagnosis and guarantee that it would resolve the issue?

 

[kaye]

We are based in Sheffield about 10 miles north East of the centre.

 

[king of pipes]

you can post a request at the top of the home page for a engineer bit to far for me good luck . Kop

 

[ShaunCorbs]

do you have the plan that poly did?

 

[kaye]

Hi Shaun, I don’t at the moment no but I have asked for this from the original installer.

 

[kaye]

Pictures of the manifolds as requested. The pipe work coming from the boiler to feed these is 22mm copper BUT to the 9 port manifold where it goes into the ceiling there is a section of plastic speedfit on the flow/return which I understand has quite a significant reduction in bore (which, if the fault is caused by the feed to the manifolds being compromised then this will only serve to exaggerate this issue?)

 

[chris watkins]

The pipe work coming from the boiler to feed these is 22mm copper BUT to the 9 port manifold where it goes into the ceiling there is a section of plastic speedfit on the flow/return which I understand has quite a significant reduction in bore

It goes from copper to plastic but does the external size reduce ie. 22 to 15mm.
The flow rates through plastic are a little less but the plastic normally has less resistance due to less fittings & smoother bore.

 

[chris watkins]

You could get an idea of the flow rate by looking at the temperatures on each of the manifolds (F&R) & the temps back at the boiler with just the 9 port one on.

 

[JVTrades]

I almost jumped in earlier in the thread to say the same. A buffer tank would improve things I'm sure. Also, that's a large area - 650 cubic meters ish and a similar sized extension. Without knowing all the building specs don't know but I would suspect that the boiler at 24 KW is too small