Cheap & Simple Wet Underfloor System Layout & Contro

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I wonder if anyone can advise me on some questions that I cannot find
mentioned anywhere on the web for an simple wet UFH project.

I have just laid a 7-loop underfloor heating pipe system in my (very well
insulated) small 3 floored 3 bed family Victorian house.

I intend to use a combi-condensing boiler, and run the boiler flow heating
pipe directly to 2nos in-line conventional radiators on the ground floor. Then return that flow to the input manifold for the 4 underfloor heating loops for the wooden upper floors. (FYI – I have used old thin aluminium offset printing plates as spreader plates wrapped around the pipes!)

The upper floors' return manifold will then flow to the input manifold of the 3 heating loops of the concrete ground floor. This ground floor return
manifold will then return to back to the boiler!

I figure the traditional radiators will initially lower the water temperature down for the wooden floor input manifold. Then this lowered return water will go into the concrete floor input manifold, which will then return to the
boiler at a very cool temperature. Thus making a very efficient condensing
system! (If not too tepid)

To save costs (and as an experiment!) am intending to construct the two sets of manifolds with 22mm push-fit copper tee pipes (with 15mm reducers) and locate it under the ground floor staircase in cupboard, about 4m from the boiler using 22mm insulated copper pipes.

I will balance each loop with gate valves (or any ideas?) on the
return manifolds, and balance the system using temporary temperature gauges clamped onto each return pipe to get even return temps. I will put lever ball valves on the input manifolds for isolation purposes.

I intend to only use the in-built boiler pump to circulate the heating, and
use the in-built boiler water temperature thermostat and timer to
control the room heating temperature.

I can will make allowances to retro- fit TRVs in each room if the room on the upper floor loops only If heating is uneven. But I intend to have the heating on in all rooms constantly from November to April

Q.1. Do I need to put in any Automatic Airbleed Valves on the upper storey loops, (If so where should the AAV be positioned -Just before the return pipe goes vertically down to the manifold to catch the air?)

Or does the UFH pipes have enough water pressure to force the air bubbles 7 meters down to the ground floor manifold AAVs.

Q.2. Do I put AAV’s on BOTH the inlet AND return manifolds, or just returns?

Q3. Is this idea workable? If so can anyone recommend a decent boiler with a tough enough pump!? I have heard of intelligent pumps that are sensitive to pressure loads required and are the most suitable for UHF?
 
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For the sake of about £200 get yourself an underfloor pump thermo mixer set.

You will be unable to control the temperature of the ufh system which becomes more effecient when it takes the heat from flow it requires and then recirculates the water around the closed system mixing both flow and return automatically.


Pete
 
Lash up which will not work correctly,typical diyer style where small amount of knowledge is dangerous !
 
Your plan will not work at all. Conventional rads and ufh need to be on totally separate circuits and completely independent controls.
 
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This question shows quite a bit of imagination and clear thinking. Putting everything in series like that can work, and there is no reason why it should not work. There are three potential difficulties:

1) There may not be enough pump pressure
2) It may be hard to get it all vented
3) Controlling the heat output of the three separate sections, which will all have the same flowrate, as they are in series.

The great advantage of this plan is that you are using the heat at lower and lower temperatures as you go around the system, and the return will be well below dew point [the onset of condensation].

There are 35kW combis out there which have 7 metre head pumps as standard.

I would fit manual airvents at a few carefully chosen high points. Automatic air vents can and do leak, so unless they are all visible, they are best avoided.

If you fit thermostatic radiator valves on all but one of the radiators, leaving one with open lockshield valves, and fit all but one of each underfloor loop with an actuator, the system should work. Each group should have an effective automatic bypass. What you do not want to happen is for the boiler and pump to operate constantly on a very light load, so that almost of all the circulation is flowing through the bypasses. Weather compensation adjusted to suit the radiator flow temperature is the way to prevent this happening, and it is simplicity itself to fit this to the best combis.

You may well find that you have to do your own development work on this, which could be frustrating, but interesting.

Make sure that your home-made heat distributor plates are making good contact with the pipes, and most important of all - connect everything up and flush it thoroughly with all valves open BEFORE you connect the boiler.

Good luck!
 
Many thanks for all your advice guys.

I will take everything onboard! If it doesn't work I can always easily connect a conventional manifold system . I screeded the final ground floor loop in today, so will let you know the outcome in a month or so. Still need to buy a combi, or thinking about using the gas Rayburn cooker I have laying around with a thermal heat store. Decisions decisions!!

A Question though.
There are no rads on the upper floors to vent air from.
So, should I fit air bleed valves to each of the loops on each of the upper floors then. Or should the combi heating water pressure be enough to force the air down to the ground floor manifold where I can bleed from?
 

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