Life with Jane

[kwittintime]

X2 on the tonic water
Stay cool

[Wroughtnharv]

The water circulation is interesting. I have co-op water and a well.
That makes the co-op very nervous. Well is for irrigation.

We ran out of half inch rebar. I need sixty more pieces. That puts me at 500+ pieces of 1/2” and 100 3/8” in the slab,12,000’ of iron if you’re counting.

So I pick up the rebar Monday morning and we tidy up to be ready for pour Wednesday.

[Wroughtnharv]

Uploaded same shot twice

[Wroughtnharv]

A clarification on why the co-op is nervous about customers who have wells. One of their biggest nightmares would be for their system to go down and then suck in water from a contaminated well that a customer hasn’t isolated properly.

Now a question on how to do the Pex water system? I’m thinking I might be able to set up a manifold system where the co-op water can be channeled through the slab for heating and cooling if wanted. Right now I have the rebar in place but I could snake in some Pex line between the rebar and the propylene and bring it up into the utility room.

This evening I heard the Bob White doing her heart breaking call. I wandered up close and she came out. So I kneeled down and she acted like she was going to come up to me. She got about four feet away and just stared at me. The she meandered away. The one time I was without my phone!!!!! Double doggone darn!!! When I told Glenda about it she said she did the same thing to her earlier. You have to love nature.

[Wroughtnharv]

The idea of the Pex tubing in the slab is so doggone interesting!

Upside: hook up to well water so that when I’m watering the yard I’m also cooling off the living areas.

Downside: if I attach the tubing to the top side of the rebar it makes the installation so easy but it also mean an errant fastener ruins the system.

It also means the added pressure on the well pump to push the water through an additional couple of hundred feet of 3/4” Pex tubing.

Ideas please, I only have a couple of days to go or no go on this.

This afternoon I’ve got to deliver two round bales to a friend. He’s lending me a super spot light like the one I have for the pour. So i’m hauling two round bales down to his place, almost a 50% discount on the hay for him. I’ve also got to weld up the weld plates for the columns that go in the slab.

It’s getting exciting.

[ronspradley]

To help the extra load on current water pump you could just add a helper pump for when you are running water thru slab.


Plumbed to bypass slab system to isolate it when not using.


Scale down slab system to what you would want involved at the times you would be watering outside. If you water in the morning, what location would you want cooled in your house in the morning.



This does sound like a good idea. I will keep this in mind when I win the lottery and build my own house.


ron and pebbles

[Wroughtnharv]

Originally Posted by ronspradley

To help the extra load on current water pump you could just add a helper pump for when you are running water thru slab.


Plumbed to bypass slab system to isolate it when not using.


Scale down slab system to what you would want involved at the times you would be watering outside. If you water in the morning, what location would you want cooled in your house in the morning.



This does sound like a good idea. I will keep this in mind when I win the lottery and build my own house.


ron and pebbles

#1 rule of the lottery, you can’t win if you don’t play.

I’m going to talk to the concrete crew about adding some Pex coils to the slab. I’m looking at locating them in the living room and bed rooms. The easiest way would be to tie the Pex to the top of the rebar. But that exposes it to being damaged by the workers while doing the pour. Installing it beneath the rebar would be more difficult and I have to wonder if the net result would be more about cooling off the earth beneath the slab.

I guess I could turn on the well to the Pex line during the pour and it would make it less likely to be crushed. Plus if there is water flow I can assume it is damaged and abandon the idea.

This is fun.

[cwk]

Originally Posted by Wroughtnharv

The idea of the Pex tubing in the slab is so doggone interesting!

Upside: hook up to well water so that when I’m watering the yard I’m also cooling off the living areas.

Downside: if I attach the tubing to the top side of the rebar it makes the installation so easy but it also mean an errant fastener ruins the system.

It also means the added pressure on the well pump to push the water through an additional couple of hundred feet of 3/4” Pex tubing.

Ideas please, I only have a couple of days to go or no go on this.

I always thought that if I had the opportunity to build a house on a slab up north, I would want to add radiant floor heating. I experienced it first hand back in the 60's and thought it was great. Snow on the ground outside in NJ, the only heat in the building was in the slab, and everyone was very comfortable in a single story building.

What I did not realize is that it could be used for cooling. We don't need heat too often in north FL.


So, here are some of my thoughts for the new pour...

Run the PEX in zones instead of one very large loop. Each zone would have its own loop that physically starts and ends in the utility area (or some place where you have the manifold). Some simple ball valves and bypasses could route the well water to where you want it in the summer. Or, simply bypass it completely. The routing system could be a simple or as complex as you want it. And, the manifold design can wait until some later date.

In the winter, hot water could be run where you want it. This could be a conventional radiant floor heating system with thermostat controls, water heaters, pumps, etc.

I don't know if mounting the PEX above or below the rebar would make that much difference in cooling or heating a concrete slab. The slab is a large thermal mass. It will heat and/or cool slowly. Does the entire mass tend to be uniform in temperature? Maybe someone else can answer that question.

The size of the PEX will directly affect the friction loss of the water flow. (Did I even say that correctly?) I cannot help there. I would assume bigger is better, but not sure how big may be too big, if that is possible.

I am pretty sure that this would not work well for summer cooling with a city water system here in Florida. The frost line is very shallow in Florida. So, water pipes under the street are not buried very deep. In hot July and August we have experience warm, almost seemed hot, water entering the building and coming out the cold water faucets. I would expect well water to be much cooler, assuming the water was not being held in a large reservoir (holding tank) above ground level. Some homes in the area have aerating tanks to reduce the sulfur smell from the well water.

The cooling effects would be from fresh, cool water traveling through the slab. If water usage was very low, I would think that the effects would be small to almost non-existent.

Ron did suggest routing the water used for outside irrigation through the system. That might work very well.

I think that the main benefit of the PEX piping in the slab would be the warmth in the winter. It is quiet. It has even distribution (if designed properly; more and/or closer piping near exterior walls, large windows, etc.). Warmth would be kept for hours, or longer, if a power failure occurs. No ductwork to install and maintain. No air filters to change.

Please keep in mind I have NO EXPERIENCE and NO TRAINING on radiant floor systems. What I have read about it is from years ago and I do not have an eidetic memory.


Thanks to Brob for sharing his knowledge based on actual experience.

[Brob]

The PEX is pretty tough. I almost exclusively tie it to the top of the rebar. People walking in the wet concrete aren't going to be able to crush it underfoot. I make the crew aware and have everyone step high as they are pulling the wet concrete. The main concern is not to get a foot hung up on a coil and drag a line out of place. If it's tied properly to the rebar, it's not too big of a concern.

I do event setup as well and we run PEX to all kinds of temporary vendor and shower trailers; the water lines are exposed for a few weeks with semis, pump trucks, and 12K telehandlers running over the PEX lines repeatedly. There's not much you can do during a pour that's going to push the material beyond its limits.

[okmunky]

My understanding of in slab heating is that it is a closed loop and the liquid is not just water. There are some liquids that transfer heat better than water.

I seem to remember reading that in slab cooling was only usable in very dry climates due to condensation problems. The slab would stay wet at Thereabouts.

I’d suggest you run your Pex so that it could be a closed loop. You can always open the ends if you want later. It would be harder to close the loop later.

Google "radiant slab heating" and research.

[Hit_the_Rhod]

Charles mentioned some of these points above, but just to reiterate:

• Slab cooling isn't efficient for several reasons, 1) unless a LOT of cool water is used (as in irrigation) then the affect in minimal. 2) cold doesn't rise, so you will have a cool floor, but the rest of the room will be ambient or higher due to sun heating.

• Slab heating IS efficient (heat rises), most heating systems (Europe is a great believer in slab heating) used closed systems as discussed, with an antifreeze mixture used, not to improve heat transfer, but to prevent freezing in the event of exposure to outside air. Also, if the water is particularly hard (high mineral content) in your area, the mineral deposits in a closed system are kept to a minimum. In an ideal system, the closed water charge would be distilled water with antifreeze added, just like in a car radiator.
• More on mineral deposits: Pex is pretty smooth, and doesn't allow much for minerals to "grip" to, HOWEVER, as soon as SOME minerals "grip", it is extremely easy for follow on minerals to adhere, initially reducing the open cross section of the pipe, and eventually leading to total blockage of the pipe rendering it useless.
• To ensure the greatest heat transfer from the piping, the pex should be installed in multiple coils, think of a slinky sitting on a table coils up (not rolling away). hold the bottom coil of the slinky steady, grab the top coils and slide to one side until you have a relatively flat and long line of overlapping coils spread out across the table. These coils greatly increase the surface area exposed to the concrete, which is needed because Pex, (and ABS, which is sometimes used) are not efficient conductors of heat. Ideally these coils will be lower in the slab than you will ever drill to set a concrete anchor, because if your luck is like mine, I could have 10' of pipe in an entire slab, and the first concrete anchor I set will find it. I would want the Pex below the rebar myself.
• More on the systems in Europe. An apartment we lived in had heat supplied by a central system water heater for the entire complex. The hot water was metered as it came into our apartment, then it went to a manifold valve system with I believe 9 valves, one for each zone or room of the house. Loved to leave the bathroom floor on all the time! And the other rooms on as needed. Hot water heats the slab, warm air rises, and the entire apartment was very nice! Cost was not prohibitive either, and everything in Germany was pretty high.

Good luck with your pour, but I don't think you really have the time remaining to design your system, obtain the materials, and install the inslab piping in the time you have remaining.
Keep up the posts, I've enjoyed "lurking" in the wings watching your and Glenda's progress!

[Brob]

There are both open-loop and closed-loop systems with hydronics; meaning the closed-loop systems recirculate an antifreeze solution that goes into a heat exchange boiler to regenerate. The system I am describing is an open-loop type where the water is circulated through the circuits of coils. Each zone is a separate loop. Typically we use 3/4" PEX which doesn't seem to seriously tax the pump too much. I haven't done this on a city water system, only with a well water setup where the water is consistently around 73°. At this temperature, there are no worries about moisture as the temperature is well above the dew point. If you were running chilled water, this would be a concern, but you're basically just helping move heat out of the building.

It's most notable in front of a sunny window, with no flow, you can feel the floor get hot; with well water circulating through the room, even the sunny spot under the window stays cool. Dogs love it!

One person mentioned the city water being warm here in Florida and they are correct. The ground temperature has its own "zones" that are affected by temperature. 1-3 foot depth is highly influenced by the sun and outside temperature 3-5 feet is still noticeably influenced, 5-11 feet still gets a bit of a swing seasonally, but once you get to 12' depth, the ground temperature stays pretty constant.

Speaking again about the open versus closed-loop, I have done a couple of systems where with the opening and closing of a couple valves at the manifold, the system becomes a closed-loop recirculating water through the water heater to comfortably heat the home.

[eddndee]

Are you making the service trough in the slab accessible for future access?

[Wroughtnharv]

Originally Posted by eddndee

Are you making the service trough in the slab accessible for future access?

I only have one line going from the outside of the slab to the inside. That’s a 1” fresh water supply line. That is besides the waste line to the septic tank. There is a 2” conduit from the wall cavity to bring electric power from the meter base to the utility room. All water will be home run from the utility room just like all electrical will be run from the breaker box in the utility room. So I guess the answer is no, there is no empty circuit available for future supply through the slab.

Yesterday afternoon the concrete contractor sent me a text saying the Wednesday appointment for concrete was no longer available to us, something to do with availability of pump truck. So we’re now set up for 5:30 am Saturday for the pour.

The upside is this gives me some time to tidy up some loose ends involving the forms, just some nit picking on my part. It also gives me a chance to form up a small slab on the south side of the welding shed. That way if we end up with a partial truck load I won’t be paying for concrete that I won’t use.

I have my big light installed on the power pole I moved. It does a pretty good job. At this time I’m not going to install the other lights as they won’t be needed. However, I’m keeping them ready just in case an opening comes in and our schedule is changed. You never know

I’ve decided that I won’t go with the radiant system. Our well water is very cold, well is over two hundred feet deep. I really don’t have time to think it out and set it up in such short notice. Because of the bargain I got on the steel for the framing, 12” for $1.00 per foot vs current price of $1.05 per foot on 3” as of yesterday my outside walls will be 12” thick. I’ll have the closed cell blown in on the walls and ceiling of the whole building. Then I will fill the exterior cavity with bats so our insulation R factor will be a very good number.

This week we’re looking at our first 100 degree day of the season. Feels like will be close to 110 for the next couple of days. Oh joy.

Last night we drove forty plus miles to attend the annual shindig for our electric co-op. It was a large crowd at a high school stadium, keep in mind most small town high school stadiums are huge in Texas. The attire was Walmart come as you are with free food, goody bag, and door prizes. It was a last minute addition to the bucket list and a nice break from the routine of barn building. We won’t do it again, different, but, it’s a country thing I guess and I’m glad we did it. It gave us a whole different perspective of our electric company and their employees.