Distance between kitchen units and under floor heating

[Loz]

Hi,

 

Having wet underfloor heating put in and been doing some reading, think pipe spacing is going to be 200 but read somewhere 100 from walls & sliding doors/bi-folds - is that correct ?

What distance would people recommend from kitchen units ?  I have a run against one wall and then a 1200 gap to island, could go 200 spacing from units and have 5 pipes or 100 from the units and 6 pipe loops ?

 

Many thanks,

 

Lawrence

[Temp]

I would probably reduce the spacing to 150mm and have 7 pipes in the 1200mm gap and 150mm separation from the units.

[Loz]

12 minutes ago, Temp said:

I would probably reduce the spacing to 150mm and have 7 pipes in the 1200mm gap and 150mm separation from the units.

 

Thanks for reply, is there a recommended distance between pipes based on pipe diameter ?

[Temp]

1 hour ago, Loz said:

 

Thanks for reply, is there a recommended distance between pipes based on pipe diameter ?

 

No, it's more to do with having sufficient pipe in the floor to get enough heat into the room. Rooms like kitchens and bathrooms that have a lot of areas where you can't run pipe can benefit with having a closer spacing to make up.

 

 

[Temp]

PS There are limits on the minimum bend radius if that's what you are asking but floor layout means there shouldn't be too many bends. Especially  if you do it like this.

 

 

 

 

[Loz]

Thanks for taking time to reply, have spoken to plumber this evening, it is 18mm pipe and he says always uses 200mm spacing so guess just have to run with that, doesn't seem to be any design and said we can work it out on Friday when on site.  He did say would normally run right up to the kitchen units which doesn't sound quite right, he has done quite a few installations and is also doing boiler/rads/plumbing for which he comes recommended but the underfloor heating does seem a bit hit and miss.

[Temp]

I'd think of the future..

 

https://underfloorheating1.co.uk/blog/article/Underfloor_Heating_with_a_Ground_or_Air_Source_Heat_Pump

 

Quote

Typically, a boiler based system would be at 200mm spacing (with certain areas such as wet or high glass areas closer) and as described above heat pump systems at 100mm spacing. Customers have one opportunity to lay the Underfloor Heating and if the pipe was installed at 200mm spacing and then used in conjunction with a heat pump later, the heat pump would typically run at 55 degrees which is inefficient. For this reason we advise customers who may install a heat pump in the future to install Underfloor Heating at 100mm pipe spacing.

 

 

Edited September 7, 2021 by Temp

[Adsibob]

36 minutes ago, Temp said:

I'd think of the future..

 

https://underfloorheating1.co.uk/blog/article/Underfloor_Heating_with_a_Ground_or_Air_Source_Heat_Pump

 

 

 

Wouldn’t 100mm be more efficient for a gas boiler based system as well, on the basis that you could run it at a lower temp?

[Ferdinand]

7 hours ago, Loz said:

Thanks for taking time to reply, have spoken to plumber this evening, it is 18mm pipe and he says always uses 200mm spacing so guess just have to run with that, doesn't seem to be any design and said we can work it out on Friday when on site.  He did say would normally run right up to the kitchen units which doesn't sound quite right, he has done quite a few installations and is also doing boiler/rads/plumbing for which he comes recommended but the underfloor heating does seem a bit hit and miss.

 

This is really your call as the customer, if you are happy with the basis of your view.

 

[Nickfromwales]

5 hours ago, Temp said:

I'd think of the future..

https://underfloorheating1.co.uk/blog/article/Underfloor_Heating_with_a_Ground_or_Air_Source_Heat_Pump

I'm doing 100mm centres as standard these days as it's much better to have the additional cross sectional area for heat transfer, plus it increases the water volume in the system which helps mitigate against requirements for larger buffer tanks with HP's. 

If this is going into a screed, I'd say a minimum of 150mm centres.

11 hours ago, Loz said:

so guess just have to run with that, doesn't seem to be any design

The No.1 suicide mission with UFH is to not install the pipe in the floor correctly / fit for purpose. A quick google suggests that 18mm pipe is from PolyPipe, so I assume the plumber would get the design FOC from his merchants!! You asking how many loops there should be etc says there is not a design at present? I would want to see evidence of the requirement, for the heat loss of the room, being more than adequately met by the system. Do not accept anything less. Also ask if the UFH will run independently, eg away from the rads, as this can provoke a requirement for a buffer to stave off short-cycling of the heat source ( boiler in this case ). It's usually in the boiler manufacturers installation guidelines to mitigate against this by design.

 

13 hours ago, Temp said:

 

The reverse / inverted method of laying ( above ) also gives considerably less resistance to the flow of water. Serpentine gives you a barrow-load of 180 turns where the water must continuously completely change direction which is not great. Plus if you google some heat signature images of the two layouts, you'll see the serpentine has a warm side and a cool side, eg where the heat diminishes from the flow to the return. Reverse / inverted does not suffer this way, and this is quite significant in a system where the pipe is in screed vs slab.

 

Challenge your plumber, as you are the customer and it's your home and your money being spent in it. Use the Heat Pump / future proofing as your "angle" if you need to 'convince them' that this needs doing.   

[dpmiller]

what 18mm system is it? 16mm is more common...

[Nickfromwales]

2 minutes ago, dpmiller said:

what 18mm system is it? 16mm is more common...

Seems PolyPipe after a quick google. 18mm will of course attract a longer / large  bending radius too....   

[Loz]

45 minutes ago, Nickfromwales said:

Seems PolyPipe after a quick google. 18mm will of course attract a longer / large  bending radius too....   

Does appear to be polypipe as that is 18mm pipe that does come up with googling, will try and ring some suppliers today to see what they say, will also check that edge insulation is going to be used as none in the room at moment : https://www.colglo.co.uk/product.php?product=UFCHF1500  - seen some sites where the block insulation also goes round the edge - is that needed or is the blue tape in the link enough ?

 

Many thanks,

 

Lawrence

[Nickfromwales]

3 hours ago, Loz said:

is that needed or is the blue tape in the link enough ?

If  it's a  s creed then   blue strip will  suffice. If a  slab, probably needs an upstand of EPS or PIRR about 25mm or so thick.

[Loz]

33 minutes ago, Nickfromwales said:

If  it's a  s creed then   blue strip will  suffice. If a  slab, probably needs an upstand of EPS or PIRR about 25mm or so thick.

Many thanks for reply, it's a liquid screed so sounds like the tape is enough, cheers,

 

Lawrence

[Nickfromwales]

3 minutes ago, Loz said:

Many thanks for reply, it's a liquid screed so sounds like the tape is enough, cheers,

 

Lawrence

18mm pipes in a thin liquid screed would not be my preference! Deffo need the pipes at narrower spacing than 200mm too with a thin screed system.