Author Topic: Hydronic heating system  (Read 16481 times)

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Offline Wolvenar

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Hydronic heating system
« on: January 06, 2012, 08:31:33 am »
This will certainly be a post that is ever changing

I have been working on hydronic heating our house. We have it partially done,

Latest addition.

We have a 1950's build house, with a full concrete basement. We really wanted to get the floor heating done in our bedroom but being this is winter it would be next to impossible to pull the concrete up and replace with the same. So for the meantime I just added a wooden floor on top of the current concrete, Maybe some day we will redo this in concrete to get the added heat storage but for the foreseeable future, this will work





Beginning of (over)building the boiler (sorry some images are not so good)


Starting with the cut material



Stacked to test that it all fits, nothing welded.
Now to grind each edge to create a v shape to weld into, and generally clean the
area to weld




First weld.



Second chamber of four.



Another view

More to come, I need to find more pics, and tale some of it finished
 
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Offline philb

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Re: Hydronic heating system
« Reply #1 on: January 06, 2012, 09:34:01 pm »
Hi Wolvenar,

i'm glad to see a post on Hydronic heating systems. That makes good sense.

How far apart are the pex tubes?

I don't have a lot of experience here. but my neighbor, the house builder does. He told me to put two strands together, 6 inches apart. He has had complaints with people saying one area is warm, while next to that, it's cold. If one tube leaks in the future,  switch to the second.

A hot water heater is his heat source. For a 5000 sq ft house, it costs $150.00/ month to heat it.



Laminate floor might be a good choice here.

Offline rossw

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Re: Hydronic heating system
« Reply #2 on: January 06, 2012, 10:46:25 pm »
Wolv, got a couple of suggestions/questions.

I've seen some people nowdays retrofitting hydronics to concrete slabs by laying the pipe directly on the old slab and fixing it, then pouring a very runny slurry of concrete over it. It's self-leveling, makes a lovely smooth finish, beds the hydronics in and couples it to the old slab (if that's your wish, otherwise foam under it I guess), makes it a fairly thin skim, and gives you some thermal mass.

Also, I'm surprised you have coils crossing over each other. That was always an absolute no-no in my circles. Running a double-spiral gives you a number of advantages. Start and end come out together, you don't have to cross over any pipes so it's all low and flat and you never kink or crush a pipe, and you have alternate hot/cold pipes. Not really "cold", but "flow" and "return". So at the "feed" end where the hottest water is, is balanced out by the last of the return water beside it - so it "averages" out. At the centre of the coil (in the middle) the return water is warmest, and the hot water is coolest...  I'll find a photo if you like.

I too thought you may have put the pipes a little closer together...

Offline Wolvenar

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Re: Hydronic heating system
« Reply #3 on: January 07, 2012, 05:24:32 am »
Ross, why does it not surprise me that you are the first one to notice or mention the touching PEX.
Since this floor was built to be temporary, when the kids move out that room will be doubling in size again.
This was a remodel to add another room for our youngest who is now getting old enough to need one (leaving us in a smaller room)
So this truly is one of two experiments I have going to prove one way or another if there is truth behind the warnings.
Though it might not live long enough to be definitive since there will be another remodel in only a couple decades if destiny permits.

 I was told about never crossing (we briefly discussed it in IRC once also), I've also been told exactly  opposite "it does not matter by" very experienced contractors.  I have seen at least 4 systems set in concrete put together in the 80's that are touching/overlapping at many points in the system with no failures so far.  I tried to find reasoning for this, but there again I had no real definitive answers. The best answers I got were:
The system builds and electrical differential from the hotter and colder sides of the loops, and creates an electrical field that will break down the aluminum oxygen barrier where ever the is close contact. Another answer was as simple as: you lose efficiency as the heat transfers at each contact/near contact point. Yet another answer was that the loops cannot touch in concrete because it causes thermal stress points that damage the concrete in a short time.
 To me the second answer is debatable on the amount of efficiency losses because any which way the heat stays in the system. Secondly there are not that large of contact points if that is the true reason. Now as for the first I cannot say for sure given the way the aluminum is embedded in between layers of the PEX  plus each end of the loop is grounded to the manifolds.  This floor was from the beginning built as a quick fix meant to last however long it lasts. So I intentionally crossed and made points that are even zip tied together as I consider this a long term experiment. I have a concrete walk in front out our porch that next year I will be embedding PEX into to save my back some shoveling  grief. I plan to place PEX with several contact points with the same idea. This may or may not work out well to make a conclusion on all three theories given these are all circumstances covered between the two setups / wood concrete. In doing this I'll also answer my question on if it matters where the PEX is. The harsh temperature changes as its turned on raising from (normal) Mn cold to melting point should hasten the results.
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Offline Wolvenar

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Re: Hydronic heating system
« Reply #4 on: January 07, 2012, 05:36:26 am »
Quote
How far apart are the pex tubes?

This is mostly 16in on center, though I had to fudge a little in a couple places, the part of the room you see it more like 18. I added more shorter pieces crosswise before I put down the top than is shown in this pic.

If I were to put in concrete I generally have a pipe no farther than every 12in as per any contractor n my areas recommendation. I don't know if this spacing has anything to do with how warm or cold your climate is, or if its to be sure of even heating.

Quote
A hot water heater is his heat source. For a 5000 sq ft house, it costs $150.00/ month to heat it.
I have seen this done A LOT around here. Its cheap, but unfortunately a lot more work if and when an element fails as there is a lot more drain down.
I (over)built my own electric boiler, I'll post more on it here later.
Quote
Laminate floor might be a good choice here.

Oh yeah also, even as this would likely be considered to far spaced piping, ie to few feet of PEX it's way more than enough for this room. The walls are now VERY well insulated. and upstairs of course is heated also.

We found a deal on linoleum that we could not pass up, and since this is temporary...
 

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Offline artv

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Re: Hydronic heating system
« Reply #5 on: January 08, 2012, 05:05:07 am »
Hi Wolv,
When I did my kitchen and dining room (~300sq/ft) I started at the kitchen, ran the outside to the farthest point away (far end of dng rm), then looped back on 12" centers, so the last run coming out ran along side of the hot coming in.
I assume the hot going in transfers some heat to the cooler coming out?
If yours is only temporary, might try filling the voids with filter sand from swimming pools, might add thermal mass and would be easy to modify down the road.
It's a very nice way of heating.
I look forward to seeing more details on your boiler.
artv

Offline rossw

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Re: Hydronic heating system
« Reply #6 on: January 08, 2012, 05:15:37 am »
Here's a couple of sections of my flooring... it shows the technique to totally avoid crossovers.







In all, I used about 3600 metres (2.25 miles) of pipe in the floor....

Offline ghurd

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Re: Hydronic heating system
« Reply #7 on: January 24, 2012, 08:58:35 am »
"This will certainly be a post that is ever changing"

I'll throw this out as a silly idea-

Water leaving the floor is still pretty warm.
Cut a slot in the concrete like adding a floor drain, dig down 16"(24"?), bury a 10' piece of 4" PVC.
Just before the water goes back for reheating, send it into the big pipe.

Seems like not a super-major project (in the big picture) to get some storage?
G-

Offline Wolvenar

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Re: Hydronic heating system
« Reply #8 on: January 24, 2012, 10:04:11 am »
Interesting idea, I did ponder placing pipes under the concrete in the same manner from the side when I redo the concrete in the room beside it.. but I gave up on that idea. I have been digging down, placing drainage, insulation, and plastic,  a couple feet of sand on that, the pex then the concrete on all of it. It works well but takes a long time to heat up all of that, but takes a long time to cool also.
bI have a water table that's rather close to the floor as is. 
I think its something less than 10 feet down during parts of the year..
So without insulation the heat is carried off by the moving water from lake to lake on each side of me. 
I have a LOT of heat storage in the garage (I'll post on this later), and in other parts of the basement that I have replaced the concrete, and more to go.
Just not much to speak of in this bedroom now.
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Offline m12ax7

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Re: Hydronic heating system
« Reply #9 on: January 24, 2012, 06:20:47 pm »
Hello!

I wouldn't mind seeing a few more pics on your boiler.   Gas fired?  Open atmosphere?   What do you have planned for the boilers heat exchanger?

Offline Wolvenar

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Re: Hydronic heating system
« Reply #10 on: January 24, 2012, 09:14:14 pm »
Sorry if I didn't mention, its an electric in this post, I have 4 5500 watt elements. I will get more images soon
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Offline Volvo farmer

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Re: Hydronic heating system
« Reply #11 on: January 24, 2012, 09:19:56 pm »

A hot water heater is his heat source. For a 5000 sq ft house, it costs $150.00/ month to heat it.


Tankless? or tank?

We use a 40 gallon tank water heater to heat 1200SF (because we were pretty broke when we built this place), and I honestly believe the thing cannot transfer enough BTU to the water fast enough to be very efficient.  We're trying to heat a 5" concrete slab and I have the distinct feeling that a bunch of my burned propane is going up the flue.


Offline rossw

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Re: Hydronic heating system
« Reply #12 on: January 24, 2012, 09:31:45 pm »
We use a 40 gallon tank water heater to heat 1200SF (because we were pretty broke when we built this place), and I honestly believe the thing cannot transfer enough BTU to the water fast enough to be very efficient.  We're trying to heat a 5" concrete slab and I have the distinct feeling that a bunch of my burned propane is going up the flue.

I feel your pain. I have two, 2000 litre tanks (about 900 gallons together) that I store the heat in from whichever sources are available - evac tubes, wood burner and CHP. My floor is about the same thickness as yours, but somewhat more of it (a bit over 8,000 sq ft) and I can suck heat out of the water far faster than anything I have puts it back in. (Even the 50kW wood burner)

I don't have a propane water-heater, but I'd have similar concerns to yours.

Our old place had a 200MJ water heater for the pool, that ran on natural gas. They were most adamant that I couldn't recover more heat from the flue because the condensate that would form (by necessity) would be so acidic it would just eat everything away. (They're right - even without that, what does condense has eaten away much of the metalwork)

We also had a 150MJ "pulse" heater. This thing is basically a jet engine in a box in the roof. The "flue" is run in ordinary PVC pipe. It is claimed it is so efficient in its burning and heat extraction that there just isn't a problem. I must agree, in the years and years we had it, it never gave any problems.

Offline Wolvenar

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Re: Hydronic heating system
« Reply #13 on: March 07, 2012, 04:05:58 am »
Here is something that will likely bring me a comment or two along the lines of why would you do that.
 ::)
I finally found some images of doing this, so posting.

When I built our attached garage I put in a pit , and a downstairs room in the front of the shop.
If this was not enough I put in hydronic heating, not just in the floor but the walls of the pit, and that room!!
 :o

Of course had to line these blocks up while putting up the wall so all holes lined up close enough to do this,
and still be half of the rows above and below.
In the images here the pex was *only* touching on top temporarily,
it was even tied together in places. This was to keep the PEX stable so it would be less likely to kink as the cement was poured and vibrated in. After a few feet I would go back with the cement vibrator and pull the PEX into its final position

As the PEX went down they were separated with rebar I welded up specifically made to hold the PEX and help guide it down without kinks.
If I can find THOSE images to show how I did that I will post them.



Excuse the mess there on the left, was a long day, and cement doesn't wait for anyone, so things got tossed as they were in the road

This all makes for a very nice place to work in the cold Mn winters.. You can lean against a wall changing oil or just working under something without freezing. It also seems to had an unexpected effect.. Normally in a pit like this when someone opens the outside doors you get a massive rush of cold into the pit. Not this setup! It seems the draft is significantly slowed, to that point its barely a hint of a cool breeze by the time it reaches you downstairs.
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Offline Wolvenar

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Re: Hydronic heating system
« Reply #14 on: March 07, 2012, 04:20:04 am »
In the above you will notice most are not completely filled, this was to allow for the best connection of a cap of sorts to be made up to cover the PEX, and allow for a ridge for the pit cover boards to fit into.

Sorry about yet another blurry photo


The indents with the bolts sticking out are there to first of all make for places to strap down the cover(s)
These bolts were cut off, and ground to just inside the holes they are in. a clip like piece and bolt to hold it on are inside of those holes.
This is to give a place to clamp the tops down. The pit also doubles as a emergency storm shelter.
I have recently seen way to many houses fall into the basement in a tornado, so this is my answer to that problem
This is 18' long, and 38" wide. the end near the big door has emergency rations, water, a hatchet, flashlights, and a cell phone (no plan but would still call 911)  With 12 inch filled block and the relatively narrow area, along with a very strong cover,
I'm betting I would not WANT to survive a storm that could take this down.

Trying to make power from alternative energy any which way I can.
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