How many UFH manifolds do I need?

[Adsibob]

My house is on three floors: ground, first and second, but the ground floor itself is actually divided in three different levels:

 

1. Entrance hall and guest WC are at 0cm
2. two steps down to living room/diner/kitchen/utility (this is probably 55% of the ground floor); and
3. one step back up to a further room.

 

so technically one could say i have five floors in total. Do I need five manifolds? Another factor which i think is relevant is that there is a different floor finish on each of the 3 ground floor areas, although the subfloor is screed and same level of insulation. Entrance hallway and guest WC floor finish will be 20mm terrazzo, the living room/etc... will be 3.5mm microcement and the the further room will be 14mm engineered parquet wood.

[Barryscotland]

Best thing you can do is send your floor plans and underfloor make up to somebody like Wunda or VPS and they will give you a rough quote listing all materials, amount of zones etc.

[Dudda]

Wunda will just look at the plans. They won't really take into account the levels. I don't think the two / three steps are an issue. I've two steps between my sitting and entrance at the lower level and kitchen, living, dining and utility on the upper one all supplied by the same manifold. I find it's the same temperature everywhere. The floor finish isn't really an issue unless you'd heavy carpet but you could just reduce the flow to other areas.

If you've mechanical heat recovery ventilation it will help transfer the heat throughout the house reducing any further discrepancies in the heat provided to individual areas.

[PeterW]

No issues with levels - it will be a single manifold

[Adsibob]

So just three manifolds, one for each floor of the house and treat all three sub levels of the ground floor as one level?

[Dudda]

2 hours ago, Adsibob said:

So just three manifolds, one for each floor of the house and treat all three sub levels of the ground floor as one level?

Yes

[PeterW]

2 hours ago, Adsibob said:

So just three manifolds, one for each floor of the house and treat all three sub levels of the ground floor as one level?

Depends on size of floors as tbh you can do more than one floor with a manifold. 

[Nickfromwales]

The most important thing is that the manifold stays as the highest point in the system so it can vent air out. So one can do the rear and half of lower, and one can do entrance and the other half of lower for eg. Doubt you’ll need 3 tbh. 

Edited September 7, 2021 by Nickfromwales

[Temp]

+1

 

Our house has two floors each on three levels. One manifold per floor on the highest level works fine.

 

What you need is enough ports per manifold/floor.  Some large rooms may need two loops, smaller rooms one loop or possibly even sharing a loop if that makes sense. By making sense I mean I wouldn't share a loop between two bedrooms as some people like very different temperatures at night. In addition there is a risk to sharing loops - it only works if the heat loss/gain is similar. Don't share a loop between a cold north facing room and a south facing room with large windows.  

[Adsibob]

Thanks for the tips guys. So the ground floor area (all three sub-levels) comes to 81 square metres, with one zone covering about 15m2 of that, another coverign 35m2 and a third covering about 31m2. Would a standard manifold have enough ports to do that or am I better off fitting two?

[Temp]

4 hours ago, Adsibob said:

Thanks for the tips guys. So the ground floor area (all three sub-levels) comes to 81 square metres, with one zone covering about 15m2 of that, another coverign 35m2 and a third covering about 31m2. Would a standard manifold have enough ports to do that or am I better off fitting two?

 

One manifold for the ground floor looks fine...

 

You mention three zones (15, 35 and 31sqm). Even if the two largest (35 and 31 sqm) needed two loops each that's only a total of 5 ports (1+2+2 = 5). Manifolds come with different numbers of ports up to 12 or more.

 

Consider adding a port for a towel rail?

 

 

 

 

Edited September 8, 2021 by Temp

[Nickfromwales]

If the location of "manifold 1" sees a zone / loop that drops down and then rises again, then you'll need to allow the air that will collect in that trapped section to escape. You cannot have a zone or loop that resides above the manifold height unless you cut the pipe, expose it, and fit an automatic air vent to it, as the air then trapped would never get to the factory vent on the manifold. That secondary remote vent can be done, just it would not be my preference.

UFH loops air-lock very easily because of the extremely slow rate of flow, so beware how you design and install or you'll need to periodically purge any loops which get air-locked. That is time consuming and laborious.

[Andehh]

What's stops air bubbles forming in the "high" point of the loop, where the water then dips down... To go back up to the manifold? 

 

Does the natural flow of water just force the air back down & around until bled at the manifold? 

 

 

[Temp]

3 hours ago, Andehh said:

What's stops air bubbles forming in the "high" point of the loop, where the water then dips down... To go back up to the manifold? 

 

Does the natural flow of water just force the air back down & around until bled at the manifold? 

 

 

 

The water cant push the air bubble down hill as it tends to float back up to the high point. Water actually flows past the bubble leaving it in place. 

[Andehh]

Thanks Temp - How much of an issue is this? I imagine for those highpoints there would be a reduction in thermal transfer?

 

I would like to have both our UFH manifolds in the same location (bungalow), but one UFH will feed a series of loops a few ft higher then lowest point of the loop...bit like a U with manifold slightly higher then the loops...but a low point between!

 

Many thanks,

Andrew

[RHayes]

Re high points in loops and air locks, I will start off my saying that it isn't ideal, and that the manifold should be at the high point, however I have experience on more than one job where the ideal was not a viable solution and in one case the manifold served the floor above. In one sense this was a physics nightmare, however providing the manifold is oriented so that the loops go down before going up and providing the system is flushed with mains pressure/flow to fully purge with air, then you'll be ok, certainly on a small drop of a couple of steps as is suggested. Indeed in the job I mentioned with the loop going to the floor above providing it was installed and commissioned properly without cutting any corners there shouldn't be any issues with air locks in loops. 

[Adsibob]

How noisy are these manifolds? We may only have space on the first floor to put one above a wardrobe (which I would imagine is probably too high) or in a wardrobe. Both options involving having the manifold in a bedroom. Is that going to be audible enough to be a nuisance?

[PeterW]

13 minutes ago, Adsibob said:

How noisy are these manifolds? We may only have space on the first floor to put one above a wardrobe (which I would imagine is probably too high) or in a wardrobe. Both options involving having the manifold in a bedroom. Is that going to be audible enough to be a nuisance?

If you go with the Wilo pump then it’s virtually silent. 

[Adsibob]

5 hours ago, PeterW said:

If you go with the Wilo pump then it’s virtually silent. 

Thanks, but not sure I follow. Are you saying the noise comes from the pump rather than the manifold? If so, is this the pump you recommend: https://www.theunderfloorheatingstore.com/water-underfloor-heating/accessories/wilo-manifold-pump-pack-with-esbe-mixing-valve-unit and then my contractor can specify whichever manifold is compatible with that and meets our requirements?

 

[PeterW]

Yes 

 

Are you doing the buying or is the contractor ..?

[PeterW]

That manifold pump set linked btw is £70 more than the same from Wunda

[Adsibob]

1 hour ago, PeterW said:

Yes 

 

Are you doing the buying or is the contractor ..?

So would you recommend Wilo for other pumps which should be quiet as well? I need one to pump water from a soakaway to a sewer on an ad hoc basis, and I need another one to pump my secondary loop for a minute or so every 20 minutes

[PeterW]

Secondary pump has to be bronze or plastic. Wilo make both. 
 

Soakaway pump for ..?? Rainwater or something else ..?

[Adsibob]

1 hour ago, PeterW said:

Soakaway pump for ..?? Rainwater or something else ..?

Rainwater.

[PeterW]

So you need a sump pump then not a circulation pump.