Need Advice - zoned radiant heating

I'm not an expert either, but why would you want 4 zones??

(1) 2 story and/or very large houses may have wide temperature differences between upper/lower story or different sides of the house. Eichers are neither. Multi-zone is a solution looking for a problem in Eichlers
(2) Radiant heating, often, requires hours to get a cold house to warm temperature (compared to forced hot air). Cycling on or off the boiler to serve 4 zones seems to offer no benefit. Using the original trim values provides all the control you want (I'm told however, the trim values are not for trimming; a quarter or half turn is all the values were intended).
My neighor retro-fitted flow control values for exact "continuous" control, but he's has an engineering PhD so the world is a big problem to be solved.
(3) I suppose this kind of multi-zone control works like an auto garden sprinkler system; each zone would have a on/off electrically-operated value controlled by a thermostat; you will need to wire 4 thermostats (or find wireless thermostats) to control the values, and each thermostat would also need to turn on/off the furnance.
All this engineering looks to be like poor return for the resources necessary.
But, hey, you have to do what you have to do.

I am no expert, but the multiple zone systems I have read about have the boiler plumbed with a primary/secondary loop setup that is quite different than the existing plumbing on our Eichler's radiant heating. Given the distance from the boiler to the manifold valves it may not be easy to make the primary/secondary loop flows balance out like a modern boiler control expects.

I'd suggest that if you pursue this you contact a reputable radiant heating contractor that knows modern systems as well as the archaic systems that are in our 40 and 50 year old Eichlers.

Well, as far as I agree that multi-zoned heating system is a must
in larger houses, I don't see a reason why I would not benefit from it
even in my small Eichler. Specifically, my house is a courtyard model,
and we use mainly master bedroom at night, so I don't care so much
about temperature in a living room, small bedrooms, and kitchen.
On the other hand I would like to maintain comfortable temperature
at night in master bedroom where we sleep at night with our new born.
Of course I can achieve that by maintaining a constant temperature in
the whole house, but if I would only sen hot water to those loops which
are in the MB floor, I should see some energy savings.

I have no doubt that control system for multi-zoned heating with such
huge inertia is a complex task. Moreover, such inertia depends on many
parameters, e.g. ambient temperature outside, temperature of water
already in radiant loop and other factors.

For instance simplistic approach of cycling the furnace when
temperature hit specific point is not gonna be optimal.
I have currently retrofitted my control system to use programmable
thermostat, and the best strategy I have found so far to maintain
steady temperature in master bedroom is to start furnace at 4am
for 2 hours until 6am, and then during a cold morning temperature
is released from the floor until 10am to keep room at nice 70F.
Then during a day, outside temperature is high enough to keep
the room above 68F which is perfectly fine.
The point here is that given current daily temperature cycles,
I need to start heating couple hours _before_ room temperature drops
below 68F,which is obviously impossible to do with a simple thermostat.
But this should be relatively easy to program into some kind of
micro-controller with sufficient number of temperature sensors
(inside and outside) and ability to control independently furnace
and valves on each radiant loop. It will be just a software after all,
and I am sure I will enjoy writing it :-)
The only investment will be in hardware to control flow
of hot water to radiant loops.

I must agree that this sounds like a overengineered solution,
but hardware cost doesn't look to prohibitively expansive,
and software part looks like a lot of fun for me.
I am not planing to do it for a simple ROI, rather as a hobby,
so as long as I will not break a bank buying sensors and valves,
I should be ok and it sounds like a lot of fun for me.
Imagine: Linux powered radiant heating system :-)

I'd suggest that if you pursue this you contact a reputable radiant heating contractor that knows modern systems as well as the archaic systems that are in our 40 and 50 year old Eichlers.

I guess that modern radiant heating systems are design in a way
that they are utilizing residual heat in the water incoming
from radiant loops, and recirculate it through the system
without a need to cycle the furnace too often.
After all, once floor is already heated, the water coming back
from a radiant loop is probably still warm enough to be
recirculated without a need to heat it more with a furnace.
This should be particularly true in a scenario with multiple
radiant loops with different heat dissipation characteristics.

Well, I am afraid that in my simplistic project, I will ignore
that fact, and simply pump water from other loops through a furnace without any bypass circuit controlling optimal mixing.
After all, this is how the system is working now, anyway.

But maybe I should experiment with separating a circuit
controlling circulation pump and furnace, and provided that
incoming water is still hot enough, pump it through the system
without igniting furnace? It will not be as good as separate
bypass/mixing valve, but it doesn't look like furnace has huge
thermal capacity, so even if I cool it down unnecessarily
before next heating cycle, it should not be a big deal.

I would definitely like to talk to some radiant heat expert
to discuss all of those issues before I will do anything.
This is the main reason for me to post to this forum.
Can you suggest someone to talk to?

My email address is [email protected]

Thanks,
Przemek

Well, it's always good to look at all your options. Research as much as you like, and talk to as many experts and friends as you are inclined to. These homes (and their challenges) are half-hobby anyway so you might as well enjoy yourself :-)

And, beyond the sheer fun of the hunt, if you're not already committed to the outcome, researching is a good way to sanity check whether what you thought was a solution to a given problem really is.

Call me old-fashioned or simple-minded but, on the face of it, your situation sounds like a pretty standard call for auxillary heating. Why pay for complicated and potentially expensive changes to create a 4-zone heating control when all you really want is for the bedroom to be warmer than the rest of the house at night? There are a lot of auxillary heating solutions out there--so there's a reasonable chance you could find one that fits your aethetics, budget, and other concerns.

How about it, anyone have some experience or pointers to the latest hot technology for warming a confined space?

Jake

Jake, you're always a voice of reason, thank you.
I forgot who the audience is -- if they weren't inherently different, they wouldn't want an Eichler.
Sure, new technology is the old electric room heater -- around $50. For something more upscale and a lot more expensive ($2,800), a single (1) unit mini-split with cooling & heating.
I'm not mentioning warm blankets or pajamas -- this is gaget time.
I'm also not mentioning your approach -- frameless insulated glass but I'm digressing.