New installation proposed using 2 manifolds for zoned UFH and zoned First Floor rads

[SgtWilson1]

Hi,
I'm at the first fix stage of extensive renovation, Ground floor UFH pretty standard 16mm Alupert in 70mm screed, Hetta manifold assembly, mixing valve pump, isolators guages etc, heatmiser UH8 and stats to controls 6 circuits 5 zones. Done this a few times now and comfortable with setup and outcome.

Your, knowledge, advise an maybe experience of doing so on this part is where I would appreciate advice or input.

I would like to control all upstairs rads in the same way by using another manifold assembly, mix valve, pump but with Blanks instead of Flow meters (I've seen Emmeti schematic's showing this method), another UH8 and stats for each circuit.

The boiler is to be a new combi, there are 2 bathrooms, 4 bed about 120 square metres, suggestions on boiler size would also help

I have spoken to a plumber who has done this and he said it worked perfectly with almost instant heat at the rads when calling.

Another thing I'm not sure of, is there a need for a bypass valve or will the one in the boiler do it if needed?

The schematic below is the plan - I'll be grateful of any potential problems being flagged up.

Thanks in anticipation

 

[Johntheo5]

Why are you installing a TMV on the rads?, you will have a combi.

 

[Mister Banks]

What is the heat loss of the property? This will determine boiler output.

 

[SgtWilson1]

Why are you installing a TMV on the rads?, you will have a combi.

Only because it comes with the manifold Kit, will it cause any problems in the circuit?

 

[SgtWilson1]

What is the heat loss of the property? This will determine boiler output.

Thanks - not calculated, 30s semi, non insulated cavity, New 300mm attic insulation, 25mm external insulated render boards, Replacement 28mm DG windows, 100mm celotex floor insulation.

 

[Johntheo5]

Only because it comes with the manifold Kit, will it cause any problems in the circuit?

They may if you want to run the boiler at the same temperature as the rads for best efficiency, you need ~ 10C differential for the TMV to work properly I believe but you can allways remove it.

You have two bathrooms, do you wish to run two showers together?, if so, you will require a pretty hefty Combi, a 36kw will give a flowrate of 17.2LPM at 40C from mains at 10C, if you fit restrictors to each shower to give say 8LPM then probably OK, it should then almost certainly be big enough for your heating demands, try and get one with a low minimum output.

 

[Mister Banks]

Thanks - not calculated, 30s semi, non insulated cavity, New 300mm attic insulation, 25mm external insulated render boards, Replacement 28mm DG windows, 100mm celotex floor insulation.

A combi boiler will be very over powered when you consider that, reportedly, 80% of UK properties have a heat loss of less than 8kw. Is there nowhere that you can fit a HW cylinder?

 

[SgtWilson1]

They may if you want to run the boiler at the same temperature as the rads for best efficiency, you need ~ 10C differential for the TMV to work properly I believe but you can allways remove it.

You have two bathrooms, do you wish to run two showers together?, if so, you will require a pretty hefty Combi, a 36kw will give a flowrate of 17.2LPM at 40C from mains at 10C, if you fit restrictors to each shower to give say 8LPM then probably OK, it should then almost certainly be big enough for your heating demands, try and get one with a low minimum output.

Thanks for the info on differential, yes it should be achiveable to have the TMV at least 10 below the boiler, and I take your point I have an opt out by removing it if it is problematic.

I would think its very unlikely that two showers will run together, I was "gut" feeling 28KW would be about the mark?

 

[SgtWilson1]

A combi boiler will be very over powered when you consider that, reportedly, 80% of UK properties have a heat loss of less than 8kw. Is there nowhere that you can fit a HW cylinder?

The layout doesn't lend well to a cylinder, I take your point about energy but I need achieve the temperatures I desire for the showers.

 

[Johntheo5]

Thanks for the info on differential, yes it should be achiveable to have the TMV at least 10 below the boiler, and I take your point I have an opt out by removing it if it is problematic.

I would think its very unlikely that two showers will run together, I was "gut" feeling 28KW would be about the mark?

The 28kw will give a flowrate of 11.47LPM in the debths of winter at 5C/40C, 13.38LPM at 10C/40C & 16.05LPM at 15C/40C in the summer.

 

[SgtWilson1]

The 28kw will give a flowrate of 11.47LPM in the debths of winter at 5C/40C, 13.38LPM at 10C/40C & 16.05LPM at 15C/40C in the summer.

Thanks for that, looks the way to go for me, I did a quick check on incoming main and its 3 bar at 12LPM so that looks to be ideal.
I Appreciate your help