Zone Valves versus Zone Pumps

KevinWyman

Still waffling between zone valves (5 zones) and zone pumps (5 zones as well).  For the zone valves I would use a variable speed ECM pump. This project is on a tight budget.  It would appear on the surface that the upfront costs for the zone valve configuration would be a few hundred dollar differential. Is there a significant electrical savings for this type of control? What percentage savings might one expect?

Are there quality zone valves that are less expensive?

Charlie from wmass

I still like pumps, pump-aholic

I like the taco ball valve style zone valves but I have a hard time finding them around my parts.

Charlie from wmass

double

post

hot_rod

what 's the load

I look at how many BTU's or GPM each zone needs. If the total load "fits" within one of the small ECM/ delta P circs, like the Grundfos Alpha, Laing or Wilos then one pump and low current draw zone valves would be my choice.



You may be able to move all zones with under 50 W of electrical consumption, at design load. Perhaps only 15W with one or two zones calling.



With delta P circulators the differential bypass valve is eliminated also, taking cost and complexity as well as energy wasting.



If the zones need 8, 10 or more GPM each, pumps may be a better choice.



hr

Tim McElwain

Great answer Hot Rod

it is my feeling that these new pumps are not the all inclusive thing in all applications.

CC.Rob

low draw valves

Care to name a couple brands/models? Belimo? Caleffi? Have often looked, but not found an energy-efficient valve.



Thanks.

KevinWyman

Zoning Follow-Up

Thanks for the responses so far.

Three of the zones are cast iron radiators (still trying to figure out the pressure drop through a radiator) currently connected with large piping versus heat load and two of the zones are finned tube radiation (newest has an 007 on it).  The total heat load of the system is approximately 110,000 btuh so I might get away with the Alpha although from my research the cast iron zones ought to be "high flow, low head loss" where as the baseboard is the opposite.

Charlie from wmass

Taco ebv

are these not energy efficient. they do not draw power to stay open. Minimal power to open and close.

http://www.taco-hvac.com/en/products/Electronic%20Ball%20Valve%20(EBV)%20Zone%20Valve/products.html?current_category=69

ChasMan

They are

Indeed they are, becuase of the unique gear drive they use high-torque, high-efficiency miniature motors to open. Then when the little electronic gizmo inside senses that the power is shut off, the capacitor inside has enough stored energy to drive them closed.

Just one issue. They are noisy. One of the suposed benefits of hydronic heat is that there is no noise. I can hear an EBV open on the second floor. Sure, I got used to it after a while and almost liked the fact that I could hear it open. I needed that because once in a while the thermostat will go tick and you don't hear the valve. You get to wander down and unplug it and plug it back in to get it going again.

My sample was only five valves. All five were noisy 2 of 5 were intermitent. After replacing the head on one and messing with the other, I just scrapped them all. Others report no issues with them. I don't get it. I wouldn't put them in again if they were free. There are other efficient valves out there. Im using Z One Caleffis which is a high current jobbie and all five of them have had failed end switches. The end switch was redesigned though and I think the new end switches are going to end my zone valve troubles.

CMadatMe

Go Alpha or Similar

Style pump. 110K is not a huge load. Zone with valves, The pump will pay itself back in a couple of years. Question I have is are we doing outdoor reset? Whats the heating plant? Are we doing ODR? Why not 2 heating curves?

KevinWyman

System Detail

Boiler is going from oil-fired cast iron (circa 1936) to modulating condensing boiler with outdoor air temperature reset. Domestic hot water priority with tankless heater to replace existing tank hot water generation. Low loss header between primary and secondary. 5 zones (3 cast iron radiators and 2 copper to finned tube baseboard). Replacing the main perimeter distribution back to manifolds for cast iron zones (changing from large 3 inch perimeter distribution (supply and return) to 3/4 inch copper runs out to existing black iron pipe risers).

CMadatMe

Multiple Water Temps

Run 2 water temps. Use the boiler reset for the fin tube and a seperate mix for the cast. Vitodens 200 is an excellent choice for the app. Boiler can control 2 heating curves. Low temp curve via a Viessmann 3-way motorized mixing valve. I wouldn't even zone the rads. Use thermostatics at the rads and a Alpha pump as my system pump.  Let it fly via constant circulation. Would use another for the high temp curve system pump and again thermostatics. Could also use Vitorols to provided indoor temp feedback to the boiler. Boiler will adj it's curve. May consider using a Vitotrol 300 for the main space. Will give you control of the boiler without going to the basement.