HVAC - Rooftop Elec. and Zone Sys. Pt. 2

This is how I do a zone system on the cheap. Bare minimum of material. Total outlay of cash is well under a grand. This system still needs work... starting with a new package unit.

Category:

Education

Tags:

• HVAC
• Rooftop
• Elec
• Electrical
• and
• Zone
• Sys
• System
• Bypass
• Damper
• Motorized
• DuroZone

[steeveazerty]

hello man, i have seen plenty video.Very good job, so thank you.

I wanted to know...do you have repair a semi hermetic compressor ( emmerson copeland or something else ). And if it was possible to see it.

And ideally, if you put some stategic pop up information in your video because i don't understand all the operations

[PutSome5tankOnIt]

@steeveazerty Thanks for the compliment and thanks for watching. I apologize for not explaining things very well. I'm not very good at computer stuff. Never worked on semi-hermetics. The biggest systems I've repaired are 5 ton (and smaller) residential equipment.

[PutSome5tankOnIt]

These were the first dampers with Belimo servo motors I've worked with. They're power open/power close but not hard to figure out. I'm used to dampers that power to close and use a spring return to open. They're a simple design that can be reconfigured for a power open/spring return application. Start collar installation is easy with a pair of dividers and a decent pair of snips. It takes an extra minute to cut a perfect hole. Time well-spent, in my opinion.

[pclle]

What happens to the airflow that's not needed in other zones that don't require cooling/heating? Does it dump or do you just cut back. Is there any means of capacity modulation to compensate for loss of airflow during low load periods when only one or two zones call?

[PutSome5tankOnIt]

@pclle The SPRD bypasses excess air from the supply plenum to the return. In theory, static pressure (and volume) is increased if only one zone calls. That zone should satisfy the thermostat fairly quickly. The hope is that the zone is brought to temp before any limits are reached.

[pclle]

@PutSome5tankOnIt So by bypassing air into the return wouldn't that cause either a freeze up or high limit lockout at some point?

[PutSome5tankOnIt]

@pclle Reaching temp limits is assured if one of the thermostats is left in the off position. This type of zone system is used to keep temperatures in different zones 'even'. It's a helluva lot cheaper than a VAV system with multi-stage heating/cooling and variable speed blower.

[NLBheating]

Great job, 5tank!! It's nice to see a properly sized (snug fitting) hole cut for the starting collar. I noticed that the damper motors were Belimos. I had Belimo motors on all of the dampers on the air-handlers at Hinsdale Middle School. They were expensive as heck. They were retrofits to replace the pneumatic dampers that were previuosly on the system. Once they went to DDC Building Controls, they switched from pneumatic to Belimos and had frequency drives installed on the blowers.

[pclle]

@PutSome5tankOnIt Right on, thanks for the discussion, I've seen many systems like this, particularly Honeywell, but they do sometimes cause nuissance issues. Look forward to your videos.

[PutSome5tankOnIt]

@DrZarkloff You're talking about a variable air volume system, right? I have zero experience on those. All motorized dampers I've seen are controlled by low voltage servo motors. They all move at a snail's pace. The control boards also take their sweet time sending signals to the dampers. Homeowners aren't 'shocked' by instant air volume changes at the registers when dampers take a minute or two to transition between the open and closed positions.