Month: November 2017


We’ve seen it before.

A tech diagnoses a failed blower relay or board so they leave the blower jumped out by putting a terminal multiplier on the common terminal of the relay/board and connecting the fan speed tap right to power.

There can be an issue with that.

Some electric heat fan coils have a heat/blower interlock where the heat relay/sequencer back feeds and brings on the blower across normally closed (NC) contacts. The purpose of this is to ensure the blower comes on with a heat call without the need for a G call.

In some circumstances when you put in a terminal multiplier and constant power the blower, the G call sends that constant power back to the Heat strips and brings them on.

Not good… high power bills, melted wires, fire, death and stale doughnuts.

So, if you are leaving a blower jumpered out to run constantly I advise doing it separate from the board completely.

Coincidentally the photo at the top is a setup that will not back feed because it uses two isolated circuits on the Heat sequencer for fan and heat…. so the photo I chose wasn’t the best. Cut me some slack, the blower assembly was sitting right behind my office.

Here is a video on what I’m talking about.

— Bryan

There are several types of Ice Machines but in this article, we will focus on Cuber style and Flaker or Nugget style. Both types produce Ice but the process of freezing and harvesting is a little different. The application in which the Ice will be used will determine what style of machine is needed. I primarily work with Restaurants and Hospitals so my article will be geared in that direction.

Let’s start by simplifying the ice making process, if we take water and circulate it over an evaporator that is below freezing we will at some point start to freeze that water, once our Ice has formed we than harvest the ice and start our process again. That’s about as simple as it gets

The steps to make Ice seem simple take water and freeze it, but It’s not that simple. Making Ice cubes is actually a pretty complicated process, with several critical steps that must be met for the process to work correctly. The first step starts with properly cleaning the water that will be made into the ice to remove any impurities, water itself naturally contains minerals and those minerals are an Ice Machines worst enemy. The minerals lead to calcium buildup which causes issues with the ice machine. A quality ice machine install will have a high-quality water filter system installed that was sized properly and has the appropriate filters inside that are chosen after a water quality test has been performed. Once we have properly filtered water we bring the water into a reservoir inside the machine and the water waits until the machine is ready to make Ice.

Among all the ice machine manufacturers there are several methods that the machine will tell itself that the ice storage bin is low on Ice and to turn on, the most common methods are a thermostat and or some sort of mechanical control that is actuated by ice buildup, subsequently telling the machine that the ice is low and it’s time to turn on.

Cuber style ice machines

Assuming the machine is ready to turn on, most brands of ice machines will start in a pre-chill, which means we cool the evaporator with no water running over it, this is done to try and prevent slush from forming. Than by means of a water pump the machine will start to circulate the water over the evaporator, and that water will continually run over the evaporator and down into the sump than it will be pumped over the evaporator again, each time it passes over the evaporator the water will get colder and colder and eventually a little bit of the water will start to freeze to the evaporator plate, this process will continue over and over again until the ice is the proper thickness. The thickness can be determined by many methods including a thickness sensor, water level monitoring, and or a timer. Once it’s time to harvest the ice the most popular method is to introduce hot refrigerant from the discharge of the compressor into the evaporator and subsequently melt the ice off the evaporator from the inside out while running a little bit of water over the cubes to assist dropping the cubes off the evaporator. The harvest cycle is usually terminated by a timer that is in the circuit board. Each manufacturer has their own unique way of making and harvesting the ice. With all cuber style ice machines the harvest cycle is very dependent on maintaining an adequate high side pressure as their defrost depends entirely on it. When the machine is self contained and located indoors its not too hard to maintain the proper head pressure because the building will likely be conditioned, however on remote systems where the condenser is located outside we utilize head pressure control valves (headmasters) to back up the refrigerant in the condenser to reduce the condensing capacity of the condenser and subsequently raise the head pressure.

Flaker or Nugget style Ice machines

These machines have a unique way of making ice they utilize a round cylinder evaporator that has an auger inside of it that is turned by a high torque gear motor. The auger sits directly In the center of the evaporator with less than 1/16th of an inch clearance on either side and the auger is always spinning it has the shape of a corkscrew. The machine will have a water reservoir that supplies water to the evaporator whenever it gets low. The machine will start to freeze the water and as it becomes ice the continually turning auger will force the ice up to the top of the evaporator and out of a nozzle that will shape the ice into the desired style (Crushed, Flaked, and or Nugget). It is important to notice that with this style of ice machine the harvest cycle happens when the ice gets thick enough for the auger to scrape it off and it both freezes and harvests the ice at the same time.

— Chris Stephens

P.S. – we have a new podcast out on ice machines HERE enjoy

My Grandfather is a really interesting guy. He grew up working in the Pennsylvania coal mines starting at the age of 7 or 8 and then worked as well driller, and a plumber, also went to HVAC school, and did some gas work worked a while as an electrician, welder, diver and ended up as an aircraft salvage man.

One of his favorite phrases is to call adjustable wrenches and channel locks (slip groove or tongue and groove pliers) “shoemakers tools”. I literally have no idea WHY he would call them that, or why he thought it was so funny to call them that but he certainly didn’t mean it as a compliment.

It is usually best to use a properly sized socket or wrench to do a job rather than reaching for a “multi-purpose” wrench, but every tool has a purpose and if you are going to use a tool it’s best to use it properly. I know this is basic, but we cant assume everyone has a grandpa like mine.

Pull Don’t Push (When You Can)

Whenever possible orient the wrench so that you are pulling rather than pushing (Yes, I know I’m awkwardly pushing in the GIF below) . This is a much more smooth and natural motion and you will be able to apply more force.

Pipe Wrenches are Special

A pipe wrench is only for working with pipe, NOT nuts, and bolts. I know this should be obvious but I worked with a guy once who treated a pipe wrench like a regular wrench and left a lot of damaged bolt heads in his wake.

A pipe wrench has sharp, angled teeth that will grip in one direction and release in the other direction. Open the jaw wide enough that the pipe sits in about the center of the pipe wrench unlike a typical where the object to be turned sits all the way in the back of the jaws.

Keep in mind that a pipe wrench will leave marring on the surface of the pipe, if you don’t want it to be damaged you can use a leather (or even rubber) strap around the pipe to protect it before using the wrench. A leather belt can do the trick.

Turn the Wrench Toward the Bottom Jaw

Maybe there is an exception to the rule, but not in any of my wrenches. If you turn the wrench toward the bottom jaw they will grip properly and be less likely to slip. In order to tighten vs. loosen just flip the wrench over and turn the opposite direction

Righty Tighty is Annoying

Half my childhood was HAUNTED by the phrase righty tighty, lefty loosey. IT IS ROUND! there is no right or left unless it is a reference to another direction (the top). It’s better said as clockwise tighty… and yes, I know that doesn’t sound cool.

— Bryan

 

 

 

 

 

Scroll to top
Translate »

Daily Tech Tip

Get the (near) daily Tech Tip email right in your inbox!
Email address
Name