Zone Valves vs Actuators

Mudaero

In my upcoming pex piping conversion on my cast iron radiators, I am debating the best way to set up the system. The system will service 3 zones (2nd floor [CI rads], main floor [CI rads], basement [fin tube]). So far, I have the following two ideas...

Idea #1:
I will use zone valves branched off the main supply line. Each branch will have a zone valve that connects to a manifold (3, 4, 4 loops, respectively).

Idea #2:
I will use a single manifold and will attach actuators to each loop on the manifold. The actuators would need to be grouped by zones to emulate what I am trying to do in Idea #1.

Ok, so any opinions on which option is better? Can the actuators be wired together to create a zone or do I need some type of controller to accomplish this. Same with the valves, can they be wired in series or would they require a zone valve controller? All opinions are appreciated.

Thanks.

NY_Rob

If each zone has it's own T-stat then...
Each T-Stat is directly wired to and activates a dedicated zone valve, the end switches of the three zone valves would be wired in parallel- that single connection gets connected to the TT terminals on the boiler. If any T-stat calls for heat, the zone valve end switch closes and activates the boiler.
No need for a zone controller in this configuration.

Dave H_2

How about idea number 3?

Depending upon flow rates for each one of the manifolds, maybe use a new manifold to supply each of the other manifolds. Then use actuators for the three zones.

But to answer your previous questions, the answer is yes.
I know its vague, but you can do either option depending upon space of mechanical room......
And yes, you can wire actuators together to operate the same zone.

Dave H.

Mudaero

Thanks for the input guys. In regards to the actuators, would they be wired similar to the zone valves above? Of course, I'd imagine one would first wire all the actuators in one zone group together, then proceed to wire in parallel (if that is how they would work).

hot_rod

Pay attention to the current draw of the manifold actuators, be sure you have enough transformer when you start grouping multiple actuators on one output

Same fit he zone valves, some of the thermal motor types draw 1 amp

Hilly

Is it correct to assume there are currently no TRV's on the CI Rads? Are you planning to keep it at strickly 3 thermostats? If I was keeping just the 3 thermostats then you could do what NY_Rob said with 3 zone valves (maybe use a zone valve relay for tidiness cause they are pretty sweet) and not use any actuators on the manifolds. Or if you need a different temperature for the fin-tube you can setup a 2-pump header. One pump and mixing valve feeds fin-tube manifold and second pump feeds two zones that feed the separate CI Rad manifolds.

(Maybe somebody else can chime in on the mixing temperature. When doing so it's rule of thumb to pump away from the mix but can you utilize mixing with good success if you only plan to use one system pump and then zone with ZV's?)

Solid_Fuel_Man

I think zone valves will work out to be cheaper, but if one fails you loose a whole zone. Depending on how many radiators total you have you could end up with quite a few actuators.

Taylor

Hilly

Solid_Fuel_Man that's what I was thinking too, he's at 11 actuators, but still only 3 thermostats so I don't see the cost benefit of actuators in this case.

Mudaero

Correct, there would be 11 actuators and the cost differential is one thing I'm thinking about. It comes close in cost though because of the higher price of a 3 separate manifold vs just a single manifold (even if it has more loops). And yes Hilly, there are no TRVs on the CI Rads. I'm actually removing the old valves at the radiators too (well, some), so that's another reason I am going with a manifold system. To me, the zone valves seem like the right move but I figured I'd just get some other opinions. I think there's part of me too that is just like "ooh, cool new manifolds, and actuators, all in one unit, oooh gadgetry...". I mean, come on, who doesn't like gadgetry...

Mudaero

Or what about this... Right now, I'm thinking about running 1/2" pex-al-pex to each radiator from the manifold. The CI radiators are about 15 - 20 feet apart from each other in this zone. Should I decrease my number of loops by combining some of these rads into a single loop? 15000, 12000, 9000, 5000 BTUs are what each rad is capable of (not sure exactly what the real output will be). Water temp is 180 degrees. I could probably get it down 7 loops total (reworking another zone also) and that might make the actuators a better option.

hot_rod

With rads in series determine the output at average water temperature as the first rads decrease the temperature to the downstream. The 1/2 Pex will be the limit in how many buts you can move.

With panel rads we suggest two, maybe 3 in series with adjustable bypass H valves.

The manifold method assures equal temperature to every rad, it give you the most adjustability, actuators can be added later, maybe even wifi actuators once they are proven.

Mudaero

What if I increased the piping to 3/4" pex? The first floor zone (the one in question here) is a relatively open space so there is no real need to adjust the radiators individually as they are not trying to heat a specific room, but simply working together to heat the 1st floor.

NY_Rob

Was the idea to set up each radiator as an independent loop?
How are you going to balance flow between loops once multiple actuators open simultaneously? One loop might have 7' head another might have 3' head, etc..
If you pipe all the radiators on a given floor in series, you only have to balance your three zones.

Mudaero

Yes, initially my idea was to set up each radiator as an independent loop. I am rethinking it now to try to lower costs and find the optimal solution. I don't imagine the head loss will differ much between loops as they will all be straight runs from the manifold. The length of the loops are relatively close in distant (the longest, 50 feet, the shortest 35 feet, approx.). I have read that piping CI rads in series can lead to lower heat down the line. But again, I'm here for ideas and opinions so I appreciate all that is being thrown my way.

Mudaero

This is the layout I am working with. The orange in the center is the boiler location in the mechanical room. The red are the radiators on the first floor. The green are the radiators on the second floor. The floor plan is from basement which I will be running fin tube around the perimeter (not completely around but just a generalization).

keyote

Use an 8 port 1-1/4 or 1-1/2" manifold on cellar ceiling and a 1/2 pex home run to each rad use the manifolds flow meter/valves to balance and a delta p pump so you don't need a Differential bypass, use the last port for the baseboard set the swt between the ideal for ci rads and baseboards [they are close] use one thermostat in the coldest room or one of the thermostats that have a remote sensor to average temps.when you get some more money if you want add trvs to the rads
ps im not a plumber so dont take my advice if its not seconded