Manifold + Cast Iron Radiators

Hilex007

I always see manifolds for radiant heat. What about manifold with uponor actuators to control individual radiator ? Did anybody see that?

delta T

I am all for manifolding radiators, but I think it is a much better system to have constant circulation set up on the system side (delta P circulation) and TRV's controlling the flow to the rads as they see fit. No need for actuators at all...

hot_rod

Thermostatic radiator valves are non-powered, wireless, and proportional control devices. A simple, accurate and relatively problem free control. They work very well with ∆P circulators to provide perhaps the most efficient zoning of hydronics.

Hilex007

Hot_rod im talking about 4 wire actuator which gives you end switch and power.

SuperJ

You could do that, you might want to look in to some sort stat that does PWM control rather than fixed dead band. A PWM stat will give shorter or longer pulses of heat depending on how far away the zone is from setpoint, giving you a bit of proportional control. Proportional control is sometimes nice on higher mass heating systems.
Otherwise the actuator is on off, rather than modulating.
What's your boiler/piping setup? Condensing? How many zone's are you planning on?
The actuators take a couple minutes to open (they rely on a wax to heat up and cool down to move the actuator).
A TRV varies the flow to the rad so you don't go from stone cold to hot, instead you go from slightly warm to hot depending on the heat loss of the room. It's much more pleasant to have some heat in the rad to break the natural convection off windows and such even if the room is at set point. You can pipe a TRV in series with a rad, and can use remote adjustment or sensing if the installed location isn't ideal.
Modulating actuators on rads will give the highest temp delta (and therefore usually boiler efficiency as well).
Home running all the stats to the manifold could be a pain in a retrofit.

Hilex007

My customer wants to convert form steam to hot water. Each room with own control. Im going with Navien NHB. I think i will do taco zone valves and CI rads

Gordy

I like KISS. Trvs, and home run rads to a manifold. Simple, and elegant proportional control of each individual emitter. Simple, and reliable, and average homeowner proof.

kcopp

Make sure you have a good air separator and a good magnetic filter back to the boiler. Especially w/ the Naiven HX. Probabaly would be a good idea to add a oxygen inhibition like Fernox or Rhomar.

Gordy

I wouldn’t pipe trvs in series. It doesn't mean you can't it just gets more involved.

Here is a link to a very informational article @Harvey Ramer wrote on the subject. His slave thermostat, and its location is a very simple way to manage the system in trvs

https://www.phcppros.com/articles/7596-a-primer-on-thermostatic-radiator-valves