DIY Hydronic Floor Heating

[AC_Hacker]

Originally Posted by Drake

This for a high thermal grout that might be used in several DIY applications that I can think of.

I think the biggest thermal contributor in MIX-111 is the silica sand. I would think that any hydronic slab floor would benefit from maximizing silica sand, consistent with strength considerations.

As I recall, directions for mixing the MIX-111 called for it to be as stiff as possible and still work with the grout pump.

Slab mix could be thicker yet, as there may not be a pump involved in the process.

* * * * *

I also recall seeing flyash and carbon additives in other thermally enhanced cementitious materials.

I do not recall ever seeing a thermally enhanced slab mix ever being mentioned in any online discussion.

Something like this could be combined with webaware's innovation.

NOTE TO WEBAWARE: you need to give this thing a name, or somebody is likely to name it for you.

Best regards,

-AC_Hacker

[pachai]

webaware, Thanks! This is great for me.
As I just had PEX installed with aluminum
staple-up plates in a new addition, now I am
thinking about the old parts of the house.
-First floor - no problem, full access from basement
-Second floor - ??? take down first floor ceiling?
(more on this below).
-Third floor - tongue-and-groove 1x8 planks,
70 years old, some have been lifted for access
already, maybe it is time to lift more of them.
(which would give me access for wiring 2nd floor :-)
Your technique would do well for me here.

First floor ceiling...
there are a few places where I have access to
the joist cavities for the first floor.
(for example, a flooded bathtub ruined the
ceiling in the foyer. I covered it with Luan
until a project like this comes along.)
The plaster on the wall on the stairs peeled
away from the lath...So I took it off and put on
drywall, but I left the ends of the joist cavities
visible behind the lath. I will propose to the
interior design team to use 1x10 to cover these,
so forever access will be an option. (Team =
wife + her friend :-)

[webaware]

Originally Posted by Drake

Webaware do you have living space above and below radiant floor? Do you plan to insulate under it to isolate space below?

Hi Drake! Living space is below - a big room heated by a radiant concrete floor.
I will be fixing 100mm fibreglass to the underside of the steel cladding for sound and thermal isolation.

[pachai]

After seeing webaware's post,
I'm reviewing in my mind the options
for putting radiant heat in existing floors.

I have easy access to the joist cavities
in much of the second floor.
The question is, can I install radiant
pipes and get the heat transfer needed?

I'm thinking some wacky things...
probably not worth it, but fun to consider.
My friend bought a tiny video camera
that he used to study a failed sewer pipe
under the sidewalk - 20' from the cleanout.

What if I found a way to put the pipe
in the joist cavity (from the stairs,
where it is open), and also put in plates...
then with the camera, I could advise
my friend how to drill small holes,
and "staple up" the plates in between
the joists, through 1/4" holes in the
plaster and lath ceiling...

Maybe there is an easier way.

[pachai]

Well,
Winter is coming, so it is time to act.

The main question I have today is,
what are people using to pump hot
water around their hydronic floors?

I went to a plumbing supply house,
and they were happy to nicely tell
me that my heating plan won't work.
But then they are willing to take
my money from me.

I priced a Grundfos at over $200,
then I bought a Bell & Gossett for $79.
And a couple of 3/4" solenoid valves.
THEN the owner walked in and
explained that the GF pump is Bronze
and won't corrode. The B&G will last
a short time and will corrode.

My question for this group is,
do I just bite the bullet, and buy the
hugely expensive pump, or
can I add something to the water to
make it less corrosive?

(In another forum, the electric car
gurus suggest using transmission fluid
as a coolant for their electric motor
controllers, because it doesn't freeze.
I plan to follow that advice for the car.
Not sure about the house :-)

Would Reverse Osmosis water be
less corrosive than potable (tap)
water with clouride and flouride
etc.? I happen to have an R-O
filter available, and could fill my
system from it. Anything else?
Adding baking soda? (now
I am just making wild guesses,
but I thought I would ask those
who are doing...while I send
my friend the Chemist a note too... :-)


Thanks alot
Seth.
I'll post a separate thread with
my idea about how to heat water....

[pachai]

Part 2 - Where does hot water come from ?
We are almost finished with an addition
that includes 800 SF that needs heat
(and cool, seasonally :-).
I have some 1500 feet of 1/2" PEX
in the floors, and now I need to figure
out how to heat the water that
will circulate.

(NOTE, this post is all about "plan B" -
next spring, we start digging to install
HDPE in the backyard for GSHP. :-)
I live in Passaic, NJ, which can get
Darn Cold in the winter.

The "main house" is heated with
a 20-year old steam boiler that is
probably double the capacity needed.
(This is based on audit trails from
my friend's Steam Manager software
that provides Zoning to the boiler
On the coldest day, the thing ran
about 6 minutes/hour.).

My thought was to tap off the main
pipe (where a radiator used to tap in),
and feed another "radiator zone" that
would basically be a pipe with a vent.
A copper pipe would be adjacent to this
"radiator" to make a heat exchanger.

I would pump fluid from a buffer tank
past this heat exchanger. Since I have
a zone controller in the system, I
should be able to turn on and off the
radiator so that I don't overheat the
PEX. I also bought a couple of 3/4"
solenoid valves.

I was thinking I could have 2 branches
downstream of the pump, one for the
heat exchanger and one for the floors.
Then it is easy, I pump the water past
the heat exchanger until it gets hot,
then switch the valves, and pump
the water through the floors until
the water is cool. Rinse,then Repeat.

Has anyone done anything similar?
(Have I explained clearly? Long day :-)
Have any feedback?
Constructive comments?
(or like the plumbing supply guys,
"feel free to throw away money" :-).

Thanks alot.
Seth

[AC_Hacker]

Originally Posted by pachai

My question for this group is,
do I just bite the bullet, and buy the
hugely expensive pump, or
can I add something to the water to
make it less corrosive?

First off, if you want a bronze pump, you can do better than the price you quoted. Check out ebay.

Second, did you use oxygen barrier PEX? If you did you are probably ok.

Third, do you have other metals in your hydronic circuit? If you have brass, you might have a galvanic situation that could corrode your iron pump. If you have stainless, no problem.

If you have oxygen barrier PEX AND no other metals (excepting stainless), you are home free.

I think that there is some kind of corrosion inhibitor, but you better verify that.

Originally Posted by pachai

(In another forum, the electric car
gurus suggest using transmission fluid
as a coolant for their electric motor
controllers, because it doesn't freeze.
I plan to follow that advice for the car.
Not sure about the house :-)

No, No, No, You will not be happy! Water has a much higher ability to convey heat.

Originally Posted by pachai

Would Reverse Osmosis water be
-less corrosive than potable (tap)
water with clouride and flouride
etc.? I happen to have an R-O
filter available, and could fill my
system from it. Anything else?
Adding baking soda? (now
I am just making wild guesses,
but I thought I would ask those
who are doing...while I send
my friend the Chemist a note too... :-)

I don't know about RO, but I would use distilled. Go for neutral pH.

Do more research.

Shop somewhere else.

-AC_Hacker

[AC_Hacker]

I just came across these graphics on a website that offers it's design services.

It is interesting because the graphics illustrate the differences in heat distribution resulting from various PEX layouts. Finite element analysis was the method to arrive at the graphics.

The pictures say it all:

-AC_Hacker

[Ko_deZ]

The pictures does give an idea on how it works. It is not accurate though.

The temperature fall is faster the higher delta T, meaning when the difference in temperature of the air and water. This will make the high temperature water drop faster than the lower temperature water.

There is also a way to reduce this temperature drop. If you have higher water speed, the water will also have spent less time in the loop, and thus, have lost less energy, giving a more even thermal distribution. That is why you should not have your loops too long, but rather put more loops in a floor in parallel. This part is not shown in the pictures. Obviously, the thermal imaging is faked (computer generated), and there are some things you can do to improve the heat spread. Having aluminium heat spread plates, preferably one that wraps around the tube, will give you a more even heat spread.

Ko_deZ

Other benefits and features of the hydronic underfloor heating system include:
pipe flexibility which permits the cabling of pipe through less accessible areas. No risk of fire or flames from a blowtorch. Easier to work with in confined spaces. Corrosion free. No scale build up. Lead free and non toxic. Less noise from water flow and expansion/contraction. Long pipe lengths reduce fittings required.