[Greenbuilding] "Succesful" Open Hydroinic Heating System

[Keith Winston]

Thanks Ward and al the radiant report! I love all these system 
feedbacks, it's always so helpful to hear how different systems are 
performing for people.

One thing is, if people start answering your question about tubing 
spacing, it's useful to distinguish between spacing in a slab (which 
really shouldn't have to be tight, since concrete is such a good 
conductor), and spacing in staple-up applications (where, actually, the 
number of heat transfer plates is more important, IMO). I place as many 
heat transfer plates as I can fit, which is probably overkill, but I 
have a semi-client (definition: someone who paid me for my time but 
didn't follow my advice) who installed a houseful of staple-up and at 
the advice of his geothermal guy left all the heat transfer plates out 
(that saves a bunch of money ;-). All the finish work is done now, and 
he can't keep the house warm. To be fair, the geothermal guy warned him 
it wasn't going to work (uh, self-fulfilling prophecy? Is the g-guy just 
partial to forced air or what?).

So to anyone else, btw, DON'T EVER INSTALL STAPLE-UP RADIANT WITHOUT 
LOTS OF HEAT TRANSFER PLATES.

That's just so I can say I told you so later ;-)

Warmly, Keith


Ward Edwards wrote:
> I installed radiant heat in my house in Ontario using an open system and 
> a Tagaki tankless hot water heater.  The house is super-insulated with 
> R40 in the walls and about R50 in the ceiling.  The house is built into 
> the side of a hill and uses passive solar design with just under 10% of 
> the floor space in south facing windows.  There is 3" of blue foam under 
> the 3.5" slab.  The pipes (pex-al-pex) are spaced at 1' intervals. I 
> have a wood stove for supplemental heat.  The heating system has a 
> single manifold and 5 loops all on the same zone.
>
> I have had no problems at all with my system which is controlled by a 
> single air thermostat near the center of the house (which is mostly open 
> concept).  The thermostat has a differential of .6C and is set at 20.5C. 
>   If it is a sunny day, the heat will not come on during the day and the 
> temperature gets to between 23C and 24C. I generally light a fire around 
> 2-3 hours after sunset before the thermostat kicks in.  The radiant heat 
> will come on about 5 in the morning if it is in the -10C to -20C range 
> and run for about 3 hours to satisfy the thermostat.  If it is overcast, 
> the system will generally start up again about 3 or 4 in the afternoon.
>
> If I am lazy and don't have a fire during the day, the floors are nice 
> and toasty for most of the day, but if I have a fire, the floors will 
> fall to room temperature during the evening.  The floors have never been 
> uncomfortably cold, but I do wear slippers most of the time.
>
> I use around 1500 liters of propane a year and about 3/4 of a cord of wood.
>
> I have seen several members mention problems with the spacing of the 
> pipes.  What are other people using?
>
> Ward Edwards
> ward at buildgreen.ca
>
> Sacie Lambertson wrote:
>   
>> Our experience with an radiant heat system with material bought from
>> Radiantec and installed by ourselves in a three inch concrete floor one inch
>> below the surface, mirrors almost exactly Ken's in Montana.   We too heat
>> with wood primarily.  We have a four zone system with inexpensive air
>> thermostats sat at 60 degrees; the in-floor heat in two of the zones, about
>> 1600 ft sq, and the majority of the main floor, almost never comes on
>> because the wood heat takes care of those spaces (we have fewer HDD in NE
>> Kansas than does Ken in Montana).  These rooms, btw have very high ceilings,
>> large windows and are generally open to each other and we run fans during
>> the winter  above the stove to distribute the wood heated air more evenly.
>> We also wear sweaters indoors during the winter.
>>
>> The radiant heat is run by a propane-fired DHW heater  which had to be
>> undersized because the vent for it was spec'd at 3 inches.  The vent was
>> buried in a concrete wall during the framing and before I figured out which
>> DHW I would buy, so there's nothing that can be done about the need for one
>> larger.  The person who designated these details also spec'd 3" under floor
>> insulation for the main floor which according to Wat John also is
>> insufficient.  I put R 20 under the basement floor but would go higher the
>> next time and would use foam (rather than Roxul).
>>
>> If we didn't have the wood stove, we would be SUTC.  Before next winter I
>> will have built/installed a solar panel system to provide pre-heated water
>> and this will make all the difference in both the amount of propane we use
>> each year (around 400 gals for all our hot water needs--we have an tankless
>> in the bathroom because the DHW could never provide sufficient hot water for
>> everything) and will also make the radiant system more efficient.
>>
>> The Radiantec system requires incoming water around 120 degrees, (which we
>> can't maintain with our current DHW tank so the floors where there is
>> radiant heat never feel nicely warm).  Five years ago we had no difficulty
>> dealing with the Radiantec folks, found them courteous and willing to
>> respond to our many questions.  The pumps and manifold system they sent us
>> are of good quality as well.
>>
>> I too would install the PEX closer together (there is a limit to its bending
>> ability though).
>>
>> Cheers,  Sacie
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