Confused

[JackofAll]

OK, so recently tried to price an all in one package(Ashp, tank and uf heating kit) but the crowd won't quote as cable tying pipes to mesh in insulated raft does not meet their spec. Just to clarify I mentioned that we didn't need pipe tracks when submitting the plans as we were cable tying to pipes. Was subsequently told that you can't do that not just by supplier but also by two plumbers? Now I believe these guys have never worked on insulated raft before and are just used to clipping to insulation. Did check out Kore raft fitting instructions and they say that pipes are not be be attached to mesh as it's structural in purpose. The 2 plumbers mentioned that fitting pipes in screed will be quicker to heat up than in concrete. Am confused.

[JohnMo]

I purchased all my UFH kit from Outsourced energy.  Just buy what you need.

 

The floor would be quicker to heat in a thin screed, but only if the insulation is directly below the screed, if it has to heat up the concrete below also it will be no quicker than in the concrete.

 

UFH isn't a radiators system it is slow, suits a heat pump as it can used at very low temperature for a long period.  Many on here have directly attached to the mesh.  Not really understanding Kore's statement on the mesh being structural as that has nothing to do with the UFH pipes.

 

UFH seems complicated when you first look at it.  But is quite simple when you actually get into the nuts and bolts of it.

 

Download a free copy of loopcad.  That will develop a plan for you to give to the plumber.  Your piping centers can be just about anything you like, I did 300mm, most do 150-200mm.  Do loops no more than 100m long.  Once you have a plan, you will have piping quantity, number of loops for you manifold etc.  Get a low temp mixer/pump such as an Ivar.

[JackofAll]

9 minutes ago, JohnMo said:

I purchased all my UFH kit from Outsourced energy.  Just buy what you need.

 

The floor would be quicker to heat in a thin screed, but only if the insulation is directly below the screed, if it has to heat up the concrete below also it will be no quicker than in the concrete.

 

UFH isn't a radiators system it is slow, suits a heat pump as it can used at very low temperature for a long period.  Many on here have directly attached to the mesh.  Not really understanding Kore's statement on the mesh being structural as that has nothing to do with the UFH pipes.

 

UFH seems complicated when you first look at it.  But is quite simple when you actually get into the nuts and bolts of it.

 

Download a free copy of loopcad.  That will develop a plan for you to give to the plumber.  Your piping centers can be just about anything you like, I did 300mm, most do 150-200mm.  Do loops no more than 100m long.  Once you have a plan, you will have piping quantity, number of loops for you manifold etc.  Get a low temp mixer/pump such as an Ivar.

Thanks John, see below from Kore, will look into loopcad.

[JohnMo]

You could do what they show or staple.  Use Pert-al-pert pipe as it is easy to form, straightens easily and bends well by hand.

[JackofAll]

What are the benefits of running the uf heating on a single zone, have seen it mentioned here but been told by others that it's mad and you need more than that?

[SteamyTea]

Easier installation, less control gear, possibly no need for a buffer or volumizer and maybe cheaper.

 

[jack]

14 hours ago, JackofAll said:

What are the benefits of running the uf heating on a single zone, have seen it mentioned here but been told by others that it's mad and you need more than that?

 

Fewer thermostats (perhaps only one), no need for per-loop actuators, no need to worry about changing flow rates as different numbers of zones are calling for heat, possibility to avoid a buffer tank (because you're always using the whole volume of the UFH loops).

 

It works fine in a well-insulated house. We've been running ours like this for 7 years without any issues.

 

If you really prefer having a zone a bit warmer/cooler than the rest, you can just manually adjust the flow rates on the manifold. I just run all of ours flat out though. 

[JohnMo]

9 minutes ago, jack said:

just run all of ours flat out though

Interesting, you don't use the flow meter or have them all fully open?

[jack]

7 minutes ago, JohnMo said:

Interesting, you don't use the flow meter or have them all fully open?

 

All fully open. Might as well minimise restrictions so the pump isn't working so hard.

[JohnMo]

If it arrives today I will be installing an Ivar mixer (to get a better control of flow temp), so may well give that a try also.

[Nick Laslett]

On 08/11/2022 at 11:11, JackofAll said:

Thanks John, see below from Kore, will look into loopcad.

@JackofAll, that is a great find. I knew from TDS Ltd’s drawings for the Kore foundation, that he wanted the UFH stapled to the EPS. It would have also helped with ICF wall prop fixings having the pipes deeper. I had my foundation installed by a Kore recommended installer. They do the insulated foundations for MBC Timber Frame. Their preference was to cable tie the UFH to the top of the mesh, which is what they did. See picture in other thread. Our slab was 150mm thick. 
 

We also have a 100mm poured concrete 1st floor. We fixed the UFH to the EPS, under the reinforcing mesh. 
 

Big fan of LoopCAD. Lots of video tutorials. Also gives heat loss calculations, very detailed. 

Edited November 9, 2022 by Nick Laslett

[JackofAll]

4 hours ago, Nick Laslett said:

@JackofAll, that is a great find. I knew from TDS Ltd’s drawings for the Kore foundation, that he wanted the UFH stapled to the EPS. It would have also helped with ICF wall prop fixings having the pipes deeper. I had my foundation installed by a Kore recommended installer. They do the insulated foundations for MBC Timber Frame. Their preference was to cable tie the UFH to the top of the mesh, which is what they did. See picture in other thread. Our slab was 150mm thick. 
 

We also have a 100mm poured concrete 1st floor. We fixed the UFH to the EPS, under the reinforcing mesh. 
 

Big fan of LoopCAD. Lots of video tutorials. Also gives heat loss calculations, very detailed. 

Just curious Nick where mesh is overlapped x 2 or3 what was the solution as the top of pipe would be very close to finished floor level. Having trouble opening loopcad as it's an exe file, haven't tried on laptop yet thought only phone so will see.

Edited November 9, 2022 by JackofAll

[JackofAll]

9 hours ago, jack said:

 

Fewer thermostats (perhaps only one), no need for per-loop actuators, no need to worry about changing flow rates as different numbers of zones are calling for heat, possibility to avoid a buffer tank (because you're always using the whole volume of the UFH loops).

 

It works fine in a well-insulated house. We've been running ours like this for 7 years without any issues.

 

If you really prefer having a zone a bit warmer/cooler than the rest, you can just manually adjust the flow rates on the manifold. I just run all of ours flat out though. 

It's mad, been told by a plumber that it would be madness to have on single zone unfortunately I wasn't smart enough to explain why it may be better to do so.

[ProDave]

14 minutes ago, JackofAll said:

It's mad, been told by a plumber that it would be madness to have on single zone unfortunately I wasn't smart enough to explain why it may be better to do so.

Mine is down to 2 zones now, once I realised the utility room has less heat input per square metre (for various reasons) and also the largest heat loss per square metre, so it was often the only zone keeping the heating on.  Now the utility is paired with another room and if it goes off before the utility is technically up to temperature, then too bad.  the utility thermostat still looks like it is doing something, even though it is not.

[Nick Laslett]

41 minutes ago, JackofAll said:

It's mad, been told by a plumber that it would be madness to have on single zone unfortunately I wasn't smart enough to explain why it may be better to do so.

I was inspired by @jack to go for the same design in principle, 1 zone for downstairs, Panasonic ASHP, no buffer tank due to quantity of water in pipes. Unlike Jack, none of this is commission, still in 1st fix. So I can’t vouch for the folly of this approach!!!
 

My understanding was with a well insulated, high level of airtightness house, with MVHR, heated by ASHP with UFC, is that having different zones has no benefit to energy usage. All the heat is contained in one envelope, and the MVHR will balance the temp across the rooms. The heat in the UFH is soaked up across the entire concrete slab during the heating season. The ASHP is running continuously, using its inbuilt weather compensation and night time set back temp. I think my target water temp is 28c, for a room temp of 22c, according to the LoopCAD output. 

Edited November 9, 2022 by Nick Laslett

[Nick Laslett]

1 hour ago, JackofAll said:

Just curious Nick where mesh is overlapped x 2 or3 what was the solution as the top of pipe would be very close to finished floor level. Having trouble opening loopcad as it's an exe file, haven't tried on laptop yet thought only phone so will see.

This is a good question. I think in places we did have 3 sheets of mesh overlap. The ducting for the hot water pipes actually created the highest points for the mesh. We have a 150mm thick slab, the mesh is sitting at 50mm, 16mm of UFH on top of the mesh. I measured the highest point, where there was mesh, UFH and duct. This was 110mm, leaving only 40mm of clearance.  Most of the foundation the height of mesh and UFH was 85mm. 
 

Is this enough clearance? Probably not. 

Edited November 9, 2022 by Nick Laslett

[JackofAll]

1 hour ago, Nick Laslett said:

I was inspired by @jack to go for the same design in principle, 1 zone for downstairs, Panasonic ASHP, no buffer tank due to quantity of water in pipes. Unlike Jack, none of this is commission, still in 1st fix. So I can’t vouch for the folly of this approach!!!
 

My understanding was with a well insulated, high level of airtightness house, with MVHR, heated by ASHP with UFC, is that having different zones has no benefit to energy usage. All the heat is contained in one envelope, and the MVHR will balance the temp across the rooms. The heat in the UFH is soaked up across the entire concrete slab during the heating season. The ASHP is running continuously, using its inbuilt weather compensation and night time set back temp. I think my target water temp is 28c, for a room temp of 22c, according to the LoopCAD output. 

My understanding was with a well insulated, high level of airtightness house, with MVHR, heated by ASHP with UFC, is that having different zones has no benefit to energy usage. All the heat is contained in one envelope, and the MVHR will balance the temp across the rooms. The heat in the UFH is soaked up across the entire concrete slab during the heating season. The ASHP is running continuously, using its inbuilt weather compensation and night time set back temp. I think my target water temp is 28c, for a room temp of 22c, according to the LoopCAD output.

 

This makes sense, just wondering what your leccy bills are like if running continuously.

Edited November 9, 2022 by JackofAll

[Nick Laslett]

30 minutes ago, JackofAll said:

 

This makes sense, just wondering what your leccy bills are like if running continuously.

Me too!  I hope once the build is finished that it delivers on some of the promises. For me I’m enjoying the self build journey, but it is a real leap of faith. MVHR, ASHP, PV, airtightness tape! This is a huge spend. 
 

HeatGeek video on zones

 

HeatGeek video on heating schedules

 

 

[Marvin]

Hmm..

 

We have AIM and APE. (Airtight, Insulation and Mvhr. ASHP, PV and EV.)

I think if I did it again I would pay more attention to the Solar gain and make the systems able to alter the east and the west facing rooms inputs independently.

 

I found, last winter, keeping the ASHP output temperature as low as possible but still keeping the desired temperature in the home, using the 'adjusted to suit our home' weather compensation alternative the most economical.   

 

Remember, the less the difference between the outside temperature and the ASHP output temperature the more efficient the ASHP runs. (But beware of short cycling)

 

Good luck.

 

M

 

[jack]

52 minutes ago, JackofAll said:

This makes sense, just wondering what your leccy bills are like if running continuously.

 

A couple of years ago, running the UFH continuously (in the sense of leaving it to look after itself - it didn't literally run continuously) through winter, we paid around £1000 for the year. That's for a 289 m2 house with decent insulation and airtightness.

 

We do have a lot of PV, so that will have significantly reduced summer electricity costs (eg, we'll have hardly used the ASHP for hot water at all during summer due to the immersion diverter heating the tank with excess solar power).

 

We've now switched to Octopus Go, which gives us 4 cheap hours of electricity overnight. With our 5 kW ASHP having to do DHW duties during that period as well, it's inevitable that some heating will need to take place outside of that time during the coldest months.

 

When it gets properly cold, I'm considering using the immersion to provide a supplementary heat boost to the DHW right at the end cheap period. Although it has a COP of 1, it's still cheaper running the immersion during the cheap period than running the ASHP during the expensive period.

 

One of the issues we face is a fairly dumb interface for the ASHP. I've started implementing some logic via our home automation system, but it's tough going with just a dry contact to call for heating and a temperature sensor for the DHW.

[JackofAll]

On 09/11/2022 at 22:21, jack said:

 

A couple of years ago, running the UFH continuously (in the sense of leaving it to look after itself - it didn't literally run continuously) through winter, we paid around £1000 for the year. That's for a 289 m2 house with decent insulation and airtightness.

 

We do have a lot of PV, so that will have significantly reduced summer electricity costs (eg, we'll have hardly used the ASHP for hot water at all during summer due to the immersion diverter heating the tank with excess solar power).

 

We've now switched to Octopus Go, which gives us 4 cheap hours of electricity overnight. With our 5 kW ASHP having to do DHW duties during that period as well, it's inevitable that some heating will need to take place outside of that time during the coldest months.

 

When it gets properly cold, I'm considering using the immersion to provide a supplementary heat boost to the DHW right at the end cheap period. Although it has a COP of 1, it's still cheaper running the immersion during the cheap period than running the ASHP during the expensive period.

 

One of the issues we face is a fairly dumb interface for the ASHP. I've started implementing some logic via our home automation system, but it's tough going with just a dry contact to call for heating and a temperature sensor for the DHW.

@jack as your PV is supplying hot water during summer months is your ASHP switched off?

[jack]

9 hours ago, JackofAll said:

@jack as your PV is supplying hot water during summer months is your ASHP switched off?

 

It's left on, but on a sunny day, the immersion diverter tends to keep the tank so warm that the ASHP won't come on, even overnight.

 

If we're using a lot of hot water for some reason, or it's cloudy, the ASHP will come on to heat the tank.

 

Also, if it's warm and sunny (especially for more than a day or two in a row), we generally run the ASHP in cooling mode during the day to keep the heat down.