using all circulator pumps on a boiler for zoning good or bad thing?

bob eck

Question when zoning a boiler with all pumps is this a good way to zone the system?
If all zones are calling for heat can the boiler be over pumped?
If that happens will over pumping drop the system efficiency?
I used to think putting pumps on all zones was the way to go.
Now with ECM pumps I would look at zoning with one pump and zone valves. If there is an indirect water heater I would still put one pump just for the IDWH and one pump for the system with zone valves.
What brand zone valves do you use?

GW

Yes Bob I guess there are different opinions. Many guys love their pumps. I tend to like the one pump and multiple zone valves. If it’s maybe 3500 sq ft house and up I may prefer pumping.

Yes the new ecm pumps are the ticket. I’ve used a ton of Alpha with trying to stick my toe in the water with Taco. I’m just silly in love with the readout on the Alpha,

I use the hw 4 wire

HVACNUT

I always thought the steel boiler and zone valves was the builders special. Now my plan is to install an Energy Kinetics Resolute with EK supplied zone valves. I have a Taco 007E ECM circ. I got from a Taco class and would like to use it as the boiler circ. I'll have to get the OK from Mr. Marran though.

New England SteamWorks

All circulators is higher end, -more reliable. More money.

Ironman

A lot depends on whether it's a CI boiler or a mod/con, and also if hydraulic separation (p/s) is being incorporated. Also, if there are multiple SWT zones in the system. There's no one size fits all answer.

hot_rod

I'd look at the load to be moved, a circ to move 1- 2 gpm doesn't make a lot of sense? Nor does 10 of them on the wall.

Ideally you want to run a pump in the middle of it's curve, which pump on this chart would you select for a 1- 2 gpm load?

ECM ∆P circulators make zoning with valves a near perfect distribution match.

Zman

I have never understood zoning with pumps for most jobs. You waste quite a bit of electricity and the pumps usually are over pumping and running on the wrong end of their curves.

Like over sizing boilers, you often see contractors that don't know how to do the math doing zone pumps just to make sure they have enough flow.

Once in a while I see a situation where you have zones with very different flow characteristics and think it would be a good application for individual zone pumps.

HomerJSmith

Zman, I do zone with circulators, UPS-15-58 3 speed, and I like zoning with them especially with Mod/Con's. It really doesn't make a difference with reservoir boiler. I always use circuit balancing valves to control the flow rate. But is is an expensive way to go on a reservoir boiler when one pump will work.

A UPS-15-58 is just almost as cheap as a cheap zone valve, and a lot more cheaper than a really good zone valve, but there are flanges added to the cost + CBVs if you go that route.

newagedawn

1 circ and zone valves, why would you want to pump more GPM through the boiler than needs to? it only takes btu's from the system

Zman

HomerJSmith said:

Zman, I do zone with circulators, UPS-15-58 3 speed, and I like zoning with them especially with Mod/Con's. It really doesn't make a difference with reservoir boiler. I always use circuit balancing valves to control the flow rate. But is is an expensive way to go on a reservoir boiler when one pump will work.

A UPS-15-58 is just almost as cheap as a cheap zone valve, and a lot more cheaper than a really good zone valve, but there are flanges added to the cost + CBVs if you go that route.

It has nothing to do with the cost of the parts. Bigger boilers don't cost much more than smaller ones, I am guessing you don't randomly double or triple the size needed.

What convinced me on this was just playing around with Siggies software. Once you realized that you can move plenty of energy with just one pump and keep it in the sweet spot on the curve it is a game changer.

The 15-58 doesn't cost much but on medium speed it costs about a penny and hour to run. This is not insignificant when you look at the lifetime of the system.

NY_Rob

I went from two 007's serving my three zones to a single Alpha now serving those same three zones w/zone valves.
I have the Alpha set on the lowest (speed 1) Constant Pressure setting. With just one zone open it only draws 11 watts, with all three open it draws 22 watts. It's an amazing little pump.
I use step modulation to throttle the boiler ramp up and it's limited to 50% firing rate so no chance of under-pumping with just one zone open and no chance of over-pumping on speed 1.

dgoldstein

Rob,

Why did you make the change from the 007 Tacos?

I have a 3-zone mod/con ODR baseboard system running a mix of 009 and 007 circs for each zone and I think a 009 on the boiler output feeding those 3-zone circs.

I almost never turn on 2 of the zones - one of them being in my utility room where the boiler and hot water heater live - it never gets colder than 60* in there.

I also seldom turn my 2nd-floor zone on since it stays around 60-70* through the winter.

NY_Rob

dgoldstein said:

Rob,
Why did you make the change from the 007 Tacos?

When I switched from a Cast Iron boiler to Mod-Con I evaluated the loop lengths and head along with the boiler requirements and it seemed the Alpha would fit the bill.. which it did. No reason for two or three circulators in a 1760 sq/ft home.

If I ran the boiler at full 80K BTU output I would need more water through the heat exchanger and would need to use a higher pump speed. Since I can run it at 40K BTU output the lowest CP speed on the Alpha pushes enough water through the HX to keep it happy with even just one zone (2gpm) open with a decent DT between SWT and RWT.

rbeck

I prefer if zoning with pumps for cast iron boilers to use p/s due to a chance of over pumping boiler assuming the boiler is proper sized mainly due to no water volume. I see many cast iron boilers with 3, 4, 6 zones or more and delta-t's of 10f to 12f. Boiler condenses more and longer. Use less zones, zone with zone valves and variable speed pumps or go p/s.
My opinion is if you are not going to size pumps for every job and every zone do p/s on all boilers. There are many makes of low wattage pumps out there today.
Protect those boilers.

hot_rod

rbeck said:

I prefer if zoning with pumps for cast iron boilers to use p/s due to a chance of over pumping boiler assuming the boiler is proper sized mainly due to no water volume. I see many cast iron boilers with 3, 4, 6 zones or more and delta-t's of 10f to 12f. Boiler condenses more and longer. Use less zones, zone with zone valves and variable speed pumps or go p/s.
My opinion is if you are not going to size pumps for every job and every zone do p/s on all boilers. There are many makes of low wattage pumps out there today.
Protect those boilers.

I'd maybe go a step further and add a buffer tank if you have a fixed output boiler, multi zoned system and low water content.

I saw a new 60K Burnham series 3 cast boiler at a trade show a few weeks back, held about 2 gallons of water! Time was when a boiler that size held 8- 10 or more. I imagine that would short cycle like a low mass copper tube boiler , regardless of zone pumps or zone valves, on a multi zoned system.

I don't see how P/S piping prevents that, it only assures boiler flow is constant, the load on the boiler determine the cycling.

NY_Rob

hot rod said:

I'd maybe go a step further and add a buffer tank if you have a fixed output boiler, multi zoned system and low water content.

IIRC there was a poster here recently with four upstairs bedrooms and each bedroom was it's own zone with it's own t-stat. Without a buffer tank how can a low mass boiler handle a 12-15ft fin-tube zone without short cycling? And if there's four upstairs zones... how many in the whole house... 6-8 zones with their own t-stats. Without a buffer tank and minimum run time and anti-cycling settings on the controller board that boiler would be on-off-on-off all day long with eight zones.