Ahhh...ducting helll

[SuperJohnG]

6 hours ago, Dan F said:

@SuperJohnG Once you've worked out ducts, make sure you have UFH layout worked out and give some thought to in-slab temp sensors (assuming you are having in-slab UFH)

I have UFH in slab, and just about to start the layouts. But was planning on just going single zone and a normal thermostat as most seem to end up with this here. Much difference using in slab temp sensor? 

[Gav_P]

23 minutes ago, SuperJohnG said:

I have UFH in slab, and just about to start the layouts. But was planning on just going single zone and a normal thermostat as most seem to end up with this here. Much difference using in slab temp sensor? 

I’ve just got a single zone for UFH (heated by ASHP) been in place for about 2.5 years now. I am thinking a slab sensor would have been a good idea. I will definitely do it next time. 

[SuperJohnG]

2 minutes ago, Gav_P said:

I’ve just got a single zone for UFH (heated by ASHP) been in place for about 2.5 years now. I am thinking a slab sensor would have been a good idea. I will definitely do it next time. 

Thanks @Gav_P any info on why you'd go for that now? I would have thought should be easy to retrofit too? 

[Gav_P]

4 minutes ago, SuperJohnG said:

Thanks @Gav_P any info on why you'd go for that now? I would have thought should be easy to retrofit too? 

Room temp can fluctuate easily kicking the heating in when not really required.

 

For example, on a day when the air temp is lower than the stat (say 13*c outside and stat is 20*c) and we open up the bifold doors for an hour, the room temp drops and equals outside temp. But the floor doesn’t lose much temp in that time(still near 20*c). However the stat is calling for heat so the floor exceeds what’s needed to try and bring the room stat back up to target. So when we shut the doors the floor is at 24*c and then we have overshoot of temp in the room. 
 

[Gav_P]

10 minutes ago, SuperJohnG said:

I would have thought should be easy to retrofit too? 

Really? How would you got about retrofitting an in slab temp sensor? I can’t picture a way of doing that.

[SuperJohnG]

8 minutes ago, Gav_P said:

Room temp can fluctuate easily kicking the heating in when not really required.

 

For example, on a day when the air temp is lower than the stat (say 13*c outside and stat is 20*c) and we open up the bifold doors for an hour, the room temp drops and equals outside temp. But the floor doesn’t lose much temp in that time(still near 20*c). However the stat is calling for heat so the floor exceeds what’s needed to try and bring the room stat back up to target. So when we shut the doors the floor is at 24*c and then we have overshoot of temp in the room. 
 

 

Makes sense now. I Guess you just turn the stat down when you do that to compensate now though?. I've not got UFH inncurrent house hence being too hot can be dealt with quickly by opening a window but witha slab its going to be hot for a while I guess? 

7 minutes ago, Gav_P said:

Really? How would you got about retrofitting an in slab temp sensor? I can’t picture a way of doing that.

I just done a little more reading and maybe not as simple as they are best in the middle of a room. I was assuming you could drill a hole somewhere inconspicuous (below a stud maybe or in a cupboardand) where you knew there wasn't a pipe  and drop it down in there.....

[Gav_P]

18 minutes ago, SuperJohnG said:

I Guess you just turn the stat down when you do that to compensate now though?.

Yeah I turn it off every time we open the house up... trouble is I’m not always here and swmbo like to open up the house as much as possible but has no idea how heating works. 

 

20 minutes ago, SuperJohnG said:

I've not got UFH inncurrent house hence being too hot can be dealt with quickly by opening a window but witha slab its going to be hot for a while I guess? 

Exactly... this is the thermal mass discussion that goes on regular here on the forum. It’s great for a steady constant temp but is slow to react and needs managing differently to ‘normal’ heating.

[Dan F]

2 hours ago, SuperJohnG said:

I have UFH in slab, and just about to start the layouts. But was planning on just going single zone and a normal thermostat as most seem to end up with this here. Much difference using in slab temp sensor? 

 

Typically each circuit will be max of 100m, so depending on the size of your house you'll likely need multiple circuits.   While you may not see the need for manually controlling each circuit seperatly in a highly insulated house you do need to ensure the system is balanced.  Three ways to balance from what I've read:

1) Adjust the flow regulators manually for each circuit on manifold based on pipe run length.

2) Use slab sensor in for each circuit and switch actuator on/off based on temperature.

3) Use the Salus auto-balancing actuators.

 

One thing to note is that option 1), won't account for areas of the slab which are potentially hotter/colder for some reason, like sun hitting fooring or near a door that gets opened regularly.

 

 

 

 

[Ferdinand]

On 22/10/2020 at 23:02, SuperJohnG said:

This is great Jamie thanks. I fortunately have 4 stations already marked out on site with Hilti nails on fencepost from when the topo was done, Just the pisser is they are all +70m from the house footprint as that was the closest solid permanent structures on site as it was a field.

 

 

Is there any reason why you can't just concrete in two or three fenceposts closer, and put your datum points on those?

 

It would need a real survey of the exact locations when set up, but should help after that. Concrete fence posts exist that come with bolt holes already in them for a mount. No one knows where the permanent structure is apart from your surveyor having surveyed it; he can surely survey a semi-permanent structure created on site.

 

That's probably what I would try and do, and I'm interested to know any reason why not. Don't you just need a slightly out-of-the-immediate way-but-close-by place on your plot that will not be disturbed during the build?

 

F

/ministry of innocent questions

[Ferdinand]

On the ducting stuff, there may be something in Jeremy's blog at mayfly.eu, as he seems to have everything everywhere eg I believe he has electrical power in 3 separate places in his garden. But I am not aware that he has listed everything in one place.

 

When I put ducts in I usually use the blue water pipe with nylon rope as a pre-installed draw string. As said above, you suck one or two through with a hoover and a moving plug such as a cloth. On occasion I have put an empty duct in the same trench as the one in use just in case the first goes tits-up, and the prices of the pipe are such that it uses a larger quantity up.

 

The possible reason for two is because some clown will always forget to tie another one on the other end at some point in the future. But you choose your level of redundancy.

 

F

[MJNewton]

12 hours ago, Gav_P said:

Room temp can fluctuate easily kicking the heating in when not really required.

 

For example, on a day when the air temp is lower than the stat (say 13*c outside and stat is 20*c) and we open up the bifold doors for an hour, the room temp drops and equals outside temp. But the floor doesn’t lose much temp in that time(still near 20*c). However the stat is calling for heat so the floor exceeds what’s needed to try and bring the room stat back up to target. So when we shut the doors the floor is at 24*c and then we have overshoot of temp in the room. 

 

Might a stat with 'open window/door detection' help there? I think it just ignores sudden drops in temperature and doesn't attempt to do anything about them. 

[SuperJohnG]

3 hours ago, Ferdinand said:

 

Is there any reason why you can't just concrete in two or three fenceposts closer, and put your datum points on those?

 

Id actually done this when I finalising the house positin after the topo. I'd created two new stations local to the house position justbto make it easier for me to mark out arcs and trainagulate all the corners. Its was only accurate to whatever the tape is but was fine for that.  Essentially yep I'll have the surveyor do the same thing when I get him back. 

 

I do have all the house and topo drawings in ACAD and use them to measure off and mark up. My friend actually has a total station so all I need to do it give him the easting and northings of the existing positions of the existing stations. Mark some new ones on my acad drawing and then I could give him all the points and set it out myself, I may do this as a backup anyway, it would save 450 but sometimes its woth paying the money to make sure its done right.  

 

The only bit I am missing is how you relate easting and northings to measurements on an ACAD drawing. But thats probably another thread I need to start..

[Ferdinand]

1 minute ago, SuperJohnG said:

 

 

The only bit I am missing is how you relate easting and northings to measurements on an ACAD drawing. But thats probably another thread I need to start..

 

I would expect a survey to give both an 8 or 10 figure grid reference and the GPS coordinates, plus ACAD to let you specify the origin point - and for that to be in the survey data.

 

But I have never used ACAD.

[SuperJohnG]

1 hour ago, Ferdinand said:

 

I would expect a survey to give both an 8 or 10 figure grid reference and the GPS coordinates, plus ACAD to let you specify the origin point - and for that to be in the survey data.

 

But I have never used ACAD.

Yeah I have full eastings and northings for the stations. I just done some reasearch and they are just metres so I can actually measure off the ACAD and provide new stations locally and then provide positions for the house and ducts etc by myself.