DIY Hydronic Floor Heating

[pachai]

Thanks. I have the next experiment in mind -
and I am working on figuring out a better heat source,
and hooking up a pump and tstat.

My recent experiments provide me some experience
with the technologies for joining PEX pipes
(or just hardware) .

There was a discussion here about this, and good
advice to invest in a Cinch tool, that makes
joining pipes a CINCH. (For unjoining, I still
need to get a nipping tool :-).

On one of my visits to HD, looking for
a quick disconnect method for PEX,
one HDer taught me how to use the
SharkBite Push-Fit system. Connectors
are expensive, but easily removable,
moreso than the Cinch clamps.

So I bought just a handful 1/2 and 3/4.
The 1/2" ones work like a champ.
The 3/4" ones - I have yet to get
both sides of a connector to accept pipe
at the same time!

I'm not asking "Is it me or is it him?" -
but does anyone know what *I* am
doing would cause this?

The HD associate showed me that
these cool things fit on various kinds
of pipes, making them a great fast way
to transition (in my view), eg, to copper.
But I have tried a few flavors of 3/4"
that I have in the house, and been
confounded!

I tried with some of the 3/4" PEX
that the plumbers used, and with
some that I bought in 10' length
from HD, which is thicker.
Same results. Tried another SB
connector, same result.

I resorted to Cinch clamps for these
connections, because the clock is
ticking, and they only cost 50 cents/clamp,
but it would be nice to be able to use
the SB system for these few connections
that need to change during testing.
Removing cinch clamps with an angle iron
is noisy at night, and the Bolt Cutter is awkward :-)

Thanks
Seth

[Ko_deZ]

Hi.

Air will leak more easily than water, making air a good test tool if done right. There are a few problems though. The guidelines below should be used:

Test with 0.5 (7,5 psi?) bar gauge pressure when using air.
Test only for two hours
Minimal pressure drops (+-0.01 bar for a short loop) is completely normal.

Why?
The pex is O2 proof, so it should not leak air, but the actual pex is plastic, and flexible. A high pressure will make it expand, and as a result, it will look like the pressure drops. Any hole that does not cause a significant pressure drop after two hours with 0.5 bar pressure will be too small for water to get trough anyway. Any hole made by a screw, nail or similar will leak quite a lot since the tube normally will collapse slightly around the penetration.
The high pressure will make the pex expand. The O2 tight layer in the pex might take damage from expanding too much (not verified, but from at trusted source).
Best way to find a leak is spraying the connectors at each end with soap water. You will see bubbles forming if there is a leak.

-Ko_deZ-

[pachai]

I mentioned in a previous post that I am still weighing my options for a heat source for the hydronic heat.
My friend came up with a plan.

He and I have the same problem - we have
space that is unheated - and we have the same
asset available - a steam boiler.
(And we both have ground source in
our long-term plans, but not this winter )

We are researching using
water spray heat recovery to
grab the heat that we currently expel
up the flue whenever the boiler runs.
If we can grab it all, the remaining vent
can be plastic instead of steel!

I'll post when I know more.
So far, it sounds really good.

Seth

[AC_Hacker]

Originally Posted by pachai

I mentioned in a previous post that I am still weighing my options for a heat source for the hydronic heat.

There's a very interesting thread you might want to look at for ideas:
Condensing Water Heater

-AC_Hacker

[pachai]

I have been inching along with my floors.
(Today is the first day of winter, time to
shift to Overdrive :-)

I have pressure-tested PEX in the floors
(mix of staple-up and embedded in tile),
and last week I bought an electric water
heater. Why an electric water heater?
Because a liquid-liquid heat exchanger
tank costs a fortune and takes time to get,
and a 40 gallon tank with electric backup
was cheap. I turned the thermostat down
to 90, and it obeyed.

I have a Bell & Gossett NRF 22 pump
(110 volts), which I plan to control with
a thermostat. I googled, and found a
widget that takes 3-12 VDC and controls
20 amps.

My primary plan for heating the water
is not electric...I would like to bounce
it off the group. It will be in more
than one phase.

1. electric (in place already, 8 more crimps :-)
By the way, Cinch connectors are great,
with the Cinch tool recommended here...
but I have bought a number of the shark bite
push connectors, and they are cool.
For "test" scenarios, like pressure testing,
it's a real time saver.
They sell a tool for releasing the connectors,
but for someone who is a "loser" (can't
find that tool this second) - "Kleins"
(electricial's pliers) work fine.

2. I have a steam boiler. One 10' long
pipe is right near my hot water tank.
My thought is to tie 2 or 4 copper pipes
to this one....so I can route
the return from the hydronic system past
this hot pipe. Heat transfer would be
by induction. I would use a
zone valve to allow water near this pipe
only when temperature warrants it.

The reason for hitting the heat source
after the load is, the heat source might
be over 180 degrees. That should not
be a problem coming into the tank
(40 gallons of 80 degree water),
but it would be a problem to go past
the heat source on the way up to the
PEX. I would sort of be using the tank
like a "mixing" valve.

3. My friend is building a flue heat
recovery system. When it is ready,
I might use it.

4. I have 3 segments of roof -
a) 375 Square feet, ESE, 20 degrees,
full of Photovoltaic panels.
b) SSW, 45 degrees, 70 square feet not
spoken for.
c) NNW, 375 square feet, clear, 20 degrees.
This roof is excluded from NJ's SREC program,
being it faces "the wrong way", but...

My thought is that roof (c) would be a fine
place for some diy parabolic troughs.
They can be tilted to face the sun...

Dan on GreenPowerScience shows one
way to make one; I have seen others;
It may be a function of what materials
I have. And how much time and money....

5. I am thinking of putting pipe in
the ground...but quotes to have
others do it are high.

6. Another option, related to #2 -
In the future, I could change my boiler's
plumbing to provide near-boiling water
in a copper pipe. I think my friend
could make me a bushing so I could thread
a 3/4" pipe through the hot water tank.
If I pump near-boiling water through that,
it would warm the tank. Again, as always,
with a thermostat and/or acquastat.

I tried to get a water heater with bolt-on
elements, because that interface is easy to
imitate, but could not. Standards are great,
except when....

The elements (I am told) are 1" straight thread,
not pipe thread. One online vendor has an
adaptor.


A question that comes to mind is, would this
need an expansion tank?
What do people do for this, other than buy
a commercial one?

Thanks alot.
Seth

[Ko_deZ]

Regarding expansion tank, yes, you certainly need one. The pressure should be between 1.6 and 2.4 bar in a floor heating system to make help make sure the pump does not cavitate. Also, you must have a pressure release valve that opens at latest 3 bar. 2.5 bar is better. With a huge amount of water, like in my 200l hwh (did the same thing as you temporarily), the pressure difference in a system varies a lot just with water temperature. I have made my own thermostat, but if you plan to up the temperature in your tank to a lot higher temperatures than the circulating, you will have temperature drops that will give you headache whenever it gets cold. Without a expansion tank there will be significant pressure changes. My friend is a plumber, and as a temporary solution he did like me, but without the expansion tank. When he opened a new circuit in the floor (concrete) he had to add quite a lot of water, about one liter, because of the cooling down of the water in the system. After a few hours, the same amount started going out from the pressure release valve, and doing so now and again for a day or so until everything was back to normal. He knows his stuff, water heating systems is his job. He said that without constant control, this system might be very expensive (new pump and such).

[pachai]

Originally Posted by Ko_deZ

Regarding expansion tank, yes, you certainly need one.

I thought I would share that I am almost
ready for a test of the system.
Here's what I have (pictures eventually).
A B&G circulator will pull water from
the Hot side of an electric water heater.
Between the tank and the pump is a Tee
and a hose bib for filling.
When I get to it, I will add a hose bib
to a water line - with a checkvalve.
The pump will push the water up to the 2nd floor
utility room, where the hydronics for the 2nd
floor break out.

I have 4 pipes from the basement to this room,
so I am using 2 up and 2 down. A 3/4x1/2x1/2
Tee splits the output of the pump.
In the future, I will try to use one 1" for
the return, freeing up 2 more for ascent.

On the return, the two "descenders"
arrive at a 3/4x1/2x1/2 Tee, to feed
the COLD side of the tank. But first,
a 1/2" line splits off to the expansion
tank that hangs above and to the side
of the water heater.

I have not installed an air vent yet;
I thought I would try an automatic one
as mentioned in GreenBuildingTalk.
I realized it needs to be
in the second floor utility room, where
the high point is...In fact, I may need two,
because there are 2 loops there.

In the future, I plan to use a thermostat
(or acquastat) to route the return,
either past a steam pipe or
through a heat exchanger of some sort.

It would be well worth it, because the
old part of the house is heated with
a gas fueled steam boiler.

More in the future, I may put pipes in the
ground for geothermal. Pipe in the ground
is expensive, so I'll need to do the math.
My friend said copper refrigerant lines
are legal in NJ only down to ten feet.
I need to check that out,
(and decide if that is worth it :-)

Another friend is a plumber, and knows
a driller, so I will speak to them about
pump and dump.

I'll post results soon, (and pics also :-)

[pachai]

Experiments are fun, but it's good to
look at the tables.
In about 5 hours, my floors have gone up
one or two degrees.

I'm checking out:
1. temperature needed to heat floors
2. flow rate needed to circulate the water
and get the turbulence needed.

The pump I am using is a
Bell&Gossett NRF-22,
which can do up to
22 GPM, and up to 15' of head.
But it doesn't say it can do 22 GPM @ 15' !

NRF-22 $85 1/25 HP
Up to 150 psi
0-22 GPM, 0-15' Head


I am considering:
NRF-36 $239.95/ each 1/6 HP
up to 150 PSI
0-36 GPM 0-34' of Head
I previously marked 4GPM on my chart;
not sure it's right, but I can check it.
PEXUniverse has a chart that says
1' head = 2PSI. I have about 20' of head =
40PSI.

I'm still working on the pictures.
(My pics are over 3 MB, about 30 times
the permitted... :-)


One question - is there a way to detect
air in the lines? Or do you just have to
"prove" it with procedure?
I put a drain with a valve at the high point,
and connected City water to the bottom,
so I don't think there are many places
I could have air...but not sure.

One remark I saw here about needing 180
degrees...made me rethink the idea of
a steam heat exchanger.
The electric hot water tank is intended to
be used for storage - the electric is
supposed to be for backup.

Seth

[ThomSjay]

Originally Posted by pachai

I'm still working on the pictures.
(My pics are over 3 MB, about 30 times
the permitted... :-)



Seth

If you have a photo software program with your camera, you should be able to 'resize' each picture as you go, while you 'export' them.
I just noticed in the reply box that there is an 'insert image' icon.

[pachai]

Originally Posted by pachai

One question - is there a way to detect
air in the lines? Or do you just have to
"prove" it with procedure? The water is
hot, but the heat is not getting to the floor.

I found out the answer is yes and no...
or yes, and yes. I called Radiantec,
who did not design my experimental
heating system, but they supplied the
staple-up plates and the PEX tubing.

The answer was, yes, there is air
in the lines. Radiantec sells a complete
Plumbing and Mechanicals kit, which
includes everything you need to get
the air out. With this kit, it's easy to get
the air out. I should have bough it.

I was afraid I would need a bigger pump.
Engineer Dan also explained to me
why I don't need a bigger pump -
which I had heard and forgotten -
With all the air out, I am not trying to
LIFT water 18-22' - rather, I am circulating
water in a 450' loop. The back pressure
from the water coming around is an offset
to the the 22' of head. When there is
air in the system, it compresses and
does not provide the back pressure,
so you are working with a much higher
work burden on the pump.

Note, I did not deliberately hold back
from buying their kit; I just bought
the pipes from them when needed,
and then forgot to go back and
design the controls.

So I studied the diagrams and pictures,
added a couple of valves and spigots to
what I had, and googled again.

Radiantec has a document on how to
purge the air (which is easy with their
plumbing and mechanical kit :-).

I worked on this Saturday night, Sunday,
sunday night... and today, I ran the pump,
and it was almost completely silent.
That is one measure of only water in
the system.

An hour or two later, I was thinking of
going to the plumbing supply house,
to get help with my boiler and my radiant...
and I checked. The floors are HOT!

(I LOVE a thermal imaging camera! :-).
My friend was between permanent F/T
jobs, so we discussed getting a thermal
imaging camera so he could do heat loss
analysis for neighbors. We never did get
any paying customers, but this is an
awesome tool. It still cost less than
a 3-zone air conditioning system.)

I can even see that the bathtub is warm
where I looped the tubing in the recesses
of the bathtub.

Originally Posted by pachai

One remark I saw here about needing 180
degrees...made me rethink the idea of
a steam heat exchanger.
The electric hot water tank is intended to
be used for storage - the electric is
supposed to be for backup.