[Strawbale] Radiator heating (off list repost)

[David Neeley]

Could someone please explain to me the advantage of a tankless heater
for a radiant floor system?

>From what I can tell, a well insulated conventional water heater
properly sized for this use is substantially the same in energy use as
a tankless, but of course at a far lower cost.

A tankless for domestic hot water can make great sense, but the nature
of the radiant floor is constant circulation when it is on, none when
it is off. Thus, the burner would work about the same in either system
with relatively little sitting around for loss from the tank--so long
as it is, as I said to begin with, adequately insulated.

A tankless large enough to do both would be prohibitively expensive, I
think. Thus, a separate heater for the domestic hot water would give a
far more cost-efficient system, while a tank-style heater for the
radiant floor would seem to give maximum bang for the buck.

Similarly, for houses where the occupants have a regular schedule, a
tank style heater that is both well insulated and working with a water
heater timer may be very close to the cost of a tankless over their
relative lifecycle. Again, it all depends upon the application.

In cases like mine, where use is likely to be intermittant all day and
most of the night--we don't keep a regular away-from-home work
schedule and I will fairly soon be working from home anyway--a
tankless system for domestic hot water makes great sense compared to a
tank. Even better would be a solar water heater, in appropriate
locations.

David

On 4/22/07, Shody Ryon <qi4u at yahoo.com> wrote:
> On Apr 22, 2007, at 03:11, Shody Ryon wrote:
>
> > I have not installed a radiant floor system.
> > Convensional wood floors are good to install a
> "staple
> > up" radiant floor system under. Are there other
> > reasons that radiant floors have been ruled out?
> > A tankless water heater requires thousands of
> dollars
> > of addtional equipment to use as a heat source for a
> > radiant system. I think this is to prevent it from
> > quickly cycling on and off. If this happens, some
> > parts will ware out quickly.
>
> Can you elaborate on this?  There are members of this
> list who use
> tankless heaters for radiant systems.  I don't
> remember them commenting
> on this.  Perhaps they will respond.  Certainly my
> tankless heater
> which I use for hot water cycles on and off
> frequently.  I wouldn't
> expect more from a system with a slow response time,
> such as what you
> get with a radiant heating system.
>
> Thank You Kindly,
>
> Corwyn
>
> The problem with tankless water heaters was not
> explained well to me. I think it is because the water
> returning from the floor to the heater would be only a
> few degrees cooler than the heater out put
> temperature. The way the fast cycling was described
> was as a "chattering". So, if I am correct, fast is an
> understatment.
> I ask too, that someone on the list enlighten the rest
> of us.
> Shody
>
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