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Gas Valve
When you look at a gas valve, imagine two valves in series.
The gas port where the tube to the pilot light connects is between the two valves, so that gas can flow to the pilot light as long as the first valve, or "safety" valve is open. If the second valve, or "main" valve is open, it can also flow to the burner trays.
Both valves are operated by electromagnets. The electric power to hold the first valve open, and therefore allow gas flow to the pilot light comes from the thermocouple or thermopile immersed in the pilot light flame. The thermocouple or thermopile generates electricity from the heat of the pilot light flame.
So, if the pilot light flame goes out, then the voltage to hold the safety electromagnetic valve open is lost and the safety valve closes, thereby shutting off gas flow completely, including the gas flow to the pilot light.
The second electromagnetic valve in the gas valve, the "main" valve, allows gas flow through a much larger tube to the burner trays. This second electromagnetic valve gets power from either a 24 VAC transformer or the thermopile. Up until recently flue dampers were not required on water heaters so 120 VAC power wasn't needed to operate hot water heaters. As a result hot water heaters typcially used thermopiles to generate more electricity than a thermocouple could, and used that electricity to operate both electromagnetic valves in the water heater's gas valve.
A thermopile is nothing more than about 25 thermocouples all connected in series, so that a thermopile generates about 750 millivolts instead of the 30 millivolts that a thermocouple produces.
On a boiler or furnace, there will be 120 VAC power available to operate the circulating pump or blower, and so by using a 24 volt transformer this 120 volt power can be converted into the same 24 VAC power that the safety controls on a boiler or furnace operate on. By simply putting the second electromagnetic valve in series with all of the safety controls, the second electromagnetic valve will open and allow gas to flow to the burner trays as long as every safety control in that "control circuit" allows power to flow through it. If any safety control detects a problem, it interrupts the circuit to that second electromagnetic valve, thereby shutting off gas flow to the burner trays (but not the pilot light).
This is where I fly off on a tangent:
Typically, the thermostat in a house won't be connected directly to that 24 VAC control circuit to the main valve in the gas valve. That's because to heat up a house you also need the boiler's circulating pump or furnace blower to come on to deliver the heat to the house. I'm much more familiar with hot water heating systems, so I'll describe the typical arrangement for a boiler. Typically the thermostat will be connected to a double pole 24 volt relay, and when that relay gets energized, it completes two circuits; a 120 VAC circuit to the boiler circulating pump or furnace blower, and a 24 VAC circuit through to the temperature control (or "aquastat") on the boiler. When power flows through that aquastat circuit, it energizes a second relay that completes a 24 VAC circuit through all the safety controls to the "main valve" in the gas valve. So, as long as the thermostat is calling for heat, the aquastat is controlling the boiler temperature setting (from 160 to 190 deg. F) and turning on and shutting off the gas valve to maintain the boiler water temperature at that setting. If the first relay completed the circuit to the gas valve directly, then the boiler would keep firing until it kicked itself out on high limit. By having that first relay control a circuit through the aquastat that controls a second relay which operates the gas valve, then the aquastat controls the gas valve to, in turn, control the water temperature in the heating system. A boiler will typically have a "ladder diagram" which shows the start up sequence as sequence of "loops" (kinda like a ladder).
Newer boilers or furnaces will simply have a "controller" that the thermostat connects to that does all this and more.
Back to the chase...
So, to diagnose a gas valve, first check to see if the pilot light is on. If so, then the thermocouple or thermopile is generating enough voltage to keep the safety valve open. If the appliance is a hot water heater but it's not firing up, the thermopile might be weak. It may be producing enough power to open the safety valve, but not enough to open both the safety and main valves together. If replacing the thermopile doesn't work, then you need a new gas valve.
If the appliance is a boiler or furnace, it'll use 24 VAC to operate the "main" valve. Check to see if you're getting 24 VAC at the terminals on the gas valve. If so, and the boiler or furnace isn't firing up, then you need a new gas valve. If you don't have 24 VAC at the gas valve terminals, check for continuity across all the safety devices in the control circuit of the boiler or furnace as it's likely one of the safety devices is interrupting the circuit to the main valve.
The "button" you have to push on a gas valve when lighting the pilot light simply overrides the first electromagnetic valve to allow gas to flow to the pilot light. Once the thermocouple or thermopile is hot enough, the electricity it generates will be sufficient to hold that electromagnet open and you can release that "button". This can often take a few seconds.
Also, thermocouples gradually lose their ability to generate sufficient voltage to operate that safety electromagnet, and when they do, gas flow to the pilot light stops. So, a pilot light that won't stay lit is often the result of an old and weak thermocouple. Different thermocouples get replaced differently. Most of the time you can just pull down on them to pull them out of a spring clip that holds them in place. Other thermocouples will be held in with a thumb screw you loosen from below to pull the thermocouple out. Basically, if it doesn't have a thumb screw on the bottom, pull down on it.
Some gas appliances, like natural gas burning fireplaces will have a "dual" pilot light that has two pilot light flames; one for a thermocouple and the other that continuously heats a thermopile. The thermocouple will produce the voltage to hold the safety valve open in the gas valve, and the thermopile will produce the voltage that goes through the control circuit to the second electromagnetic valve. In this way, the fire place can be turned on, turned up, turned down and shut off with just the turn of a switch even without external electric power being supplied to it.
This is what a thermoCOUPLE looks like:
The copper "tube" is really a coaxial cable. The outside of the cable is copper and there's an insulated copper wire that runs inside it. When the end of the thermocouple is heated, a voltage is generated between the two copper conductors.
This is what a thermoPILE looks like:
The distinguishing characteristic of a thermopile is that it connects to the gas valve with two electric wires (each with a terminal crimped onto it) rather than with a single nut like the thermocouple does.
And, finally, since both a thermocouple and a thermopile simply create a voltage difference between two wires when their ends are heated, different lengths of thermocouples will all generate the same voltage, just as thermopiles of different length. So you can use a longer thermocouple to replace a shorter one, and use a longer thermopile to replace a shorter one. They're like extension cords or garden hoses or battery booster cables in that respect. That's important to know when you're water heater's pilot light goes out and the hardware store doesn't have a thermopile of the right length. (Just buy a longer one.)
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Kitchen Remodeling Edition
The kitchen is evolving. No longer is it viewed as a place solely to prepare and cook food. Instead, it has transformed into a space that can be truly utilized for living & entertaining friends and family.
In essence, out of all the rooms in the house, the kitchen is often the family hangout. Parents are cooking or checking e-mails, the TV is on, and the kids are doing their homework — all at the same time, all in the same room.
The next generation kitchen will be a place not only for cooking, but also for social and everyday interaction. Kitchen remodeling trends now concentrate on the kitchen as the ‘hub‘of the household, incorporating the functional aspects of a kitchen with the ability to relax and enjoy the surroundings.
 
The trends in kitchen remodeling and design are set to focus on comfort and usability. Imagine a kitchen that incorporates a couch, a television, a coffee table, and internet access into its space. This is the future of kitchen design.
The kitchen space is set to evolve to incorporate all of the needs of everyday life.
As it becomes increasingly hard to juggle the tasks of every day life, this is a room to fit around your lifestyle. Having a ‘live- in room‘provides family space where you can prepare a meal while helping the kids with their homework. It is versatile and very useable.
This trend seems a natural progression in a period when open planned living has become the chosen preference for most households. Remodeling the kitchen into a live-in room therefore will add a new level of comfort and practicability to a style of living that most Americans have already adopted. As the kitchen continues to be the most used space in the household, adapting this space to be truly comfortable and useable is a key to utilizing the function of the space.
When it comes to the ductwork, kitchen remodeling requires resolving some of the most important issues, which could arise during the remodeling process.
For example:
- Bathbox installation/relocation
- High wall heat installation
- Toe kick heat installation
If in your kitchen you are doing a remodeling project on moving a wall, you may find out that existing heat no longer can serve your kitchen area and should be moved to another location. It is why I give you three options of resolving this issue:
If you have an unoccupied span of wall you can install a bath box in, if not, you can install a bath box high above your wall cabinets, or you can set it low and bring such necessary heat to your kitchen area as the Toe Kick heat.
Next and the most important part of your kitchen-remodeling project is a kitchen exhaust. Here you can also have three options:
- Microwave Hood exhaust
- Kitchen Hood exhaust
- Downdraft Range exhaust
All three of them require resolving of some ductwork installation issues and you are able to find the solutions in my book.
The “Jumper Installation” chapter of my book gives you insight on how to run heat or exhaust if you unable to run it as a “straight shot”.
All the chapters are very cheap and the book price is even cheaper than combine the price of all chapters. However, you may be worried that there is no answer to your particular question or issue, and then you have two options:
- You can buy the book and if you are unable to find an answer to your particular question I will answer it free of charge
- You can ask your question before the book purchasing and I will tell you if there is an answer in the book. You can type your question here.
Chapters of the book:
- Bath Box Installation
- High Wall Heat Installation
- Toe Kick Heat Installation
- "Jumper" Installation
- Kitchen Exhaust
- Tools and Materials
Price for the book is only $7.49, please click BuyNow button below and purchase an Instant Access to the downloadable version!
Or you can buy any of the five chapters of the book below!
What is a Range Hood
New! Buy any products from Amazon.com total value of $100.00 on my site and get any paid page up to $4.00 value free of charge! Got questions? Ask them here. Get more info here. (01/24/2012)
Instant Download:
After you have purchased a paid page, PayPal is going to bring you back to my website. In order to see the paid page you have to click on the “Register” button, fill out the form, choose your own Username and Password, click on the arrow at the top of the page, move the form up and click on the “Register” button at the bottom of the form – congratulation, you are now on the page you have paid for!
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1. Toe Kick Heat Installation – the chapter covers several topics and gives explanations:
- How to make openings in the floor and in the cabinet
- What kind of fitting should be used
- How to cut a take-off in
- How to run a pipe
- How to terminate a heat run
The chapter could be useful for the kitchen or bathroom remodeling project or to any project alike. The chapter has five pages, 10 pictures. $2.50. (Instant Access).
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2. High Wall Heat – the chapter covers several topics and gives explanations:
- How to install High Wall Heat and what kind of fitting should be used
- How to measure, cut, and put together piece of oval stack or pipe
The chapter could be useful for the kitchen or bathroom remodeling projects or to any project alike. The chapter has four pages, two pictures in it. Price of the chapter is only $2.50 (Instant Access).
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3. “JUMPER” INSTALLATION – the chapter gives explanations:
- How to run a “jumper” to the Toe Kick 90*
- How to run a “jumper” to the Oval Stack
The chapter could be useful for the kitchen or bathroom remodeling projects or to any project alike. The chapter has nine pages, twenty pictures in it. Price of the chapter is only $2.50 (Instant Access) |
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4. MICROWAVE HOOD, JENN AIR, KITCHEN HOOD
 the chapter describes all three cases of the kitchen exhausts: Kitchen Hood, Microwave Oven Hood, Jenn-Air Fan; explains the roof and wall caps installation; covers the ductwork installation. Chapter has 10 pages, 30 pictures. Price of the chapter is only $2.50 (Instant Access).
This discussion took place on the forum.doityourself.com website:
Question
I have a GE JV966DSS that calls for 7" ducting. It is rated at 600 CFM with two fans installed 30" over a 36" GE gas cook top with 5 burners. Well, the HVAC person came when I wasn't home, and installed 6" ducting instead, about 30" of it through the roof. Poor communication on my part. Should I call him back to install 7" instead? How much effectiveness did I reduce by going with 6" vs. 7"? Thank you in advance.
Answer
With 600 CFM I think 7” would be too small. I think an eight inch would be better so the static pressure is not off the chart. But I would add that I would go with what the manufacture recommend. Make sure you seal the duct because it will push any grease out the seams at that kind of pressure.
Feedback
Thanks. Well, I called the HVAC Company. They said they don't install 7" ducting. They have 8" ducting, but only install them if the hood calls for 8". He said 6" shouldn't reduce the efficiency too much. I don't agree with him as it stated clearly in the manual that going smaller will decrease the efficiency. A 15% decrease in diameter will reduce the flow by almost 50%, the equivalent of doubling the length of the pipe I suppose. With the length of my pipe at 45’, it effectively increases it to 90’, technically still below the 100 ft maximum length per manufacturer recommended. I am not happy, but they are not going to install either 7" or 8".
That’s it! But what that homeowner could do, I think you already got the answer! Of course if he would purchase the MICROWAVE HOOD, JENN AIR, KITCHEN HOOD chapter then:
- He could do it himself
- He would know how this installation should be done and hire someone
- He could ask me some questions before this started and after it’s done
I know I know the price of any home improvement project easily adds up, and even $2.50 for this chapter seems too high when you already spent hundreds of dollars on everything else. It is true, but what this guy is going to do now… have the answer?
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5. BathBox Installation – the chapter covers bathbox installation in the interior wall. The chapter  could be useful for the kitchen or bathroom remodeling projects or to any project alike. The chapter has two pages, one picture in it. Price of the chapter is only $1.49 (Instant Access). |
List of YouTube Videos
01. How to Install New Panasonic NN-SD277WR Microwave
02. Improperly Installed Microwave Found by Madison MS Home Inspector
03. Replacing Microwave Wave Guide Cover
04. Microwave Fixing
05. Range Hood Installation
06. Kitchen Cabinet Installation
07. Vent-A-Hood Introduces Duct-Free ARS Hoods
08. Vent-A-Hood Company History
09. Vent-A-Hood University
10. Kitchen Equipment: The Range Hood
11. Veneto European Range Hood Wall Mount B2W
12. PLZW Range Hood Install Slide Show
13. Do It Yourself Kitchen Installation - Part I
14. Do It Yourself Kitchen Installation Part II
15. Do It Yourself Kitchen Install Part III
16. Range Hood, To Circulate or Not Circulate |
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Finished Basement Kitchen Hood (Installation in Pictures)
On the rare occasion, people who finish their basements off put an additional kitchen. This kitchen as any other may have a microwave hood or kitchen hood and on this page you can learn how to install it.
On this page, you can see illustrations of all installation in the making except installation of the kitchen hood itself. However, if you would purchase this page by the time you will be ready to mount one I will make all necessary additional pictures and invite you back to this page.
On the page, you can see 20 pictures of the tools and materials and 9 pictures of installation that represent it in the step-by-step manner.
In order to gain an accesses to the Finished Basement Kitchen Hood (Installation in Pictures) page you have to pay an access fee of $1.34. Just click on the “Buy Now” button below. Once you pay, you will gain an instant access to the page!
Instant Access:
After you have purchased a paid page; PayPal is going to bring you back to my website. In order to see the paid page you have to click on the “Register” button, fill out the form, choose your own Username and Password, click on the arrow at the top of the page, move the form up and click on the “Register” button at the bottom of the form – congratulation, you are now on the page you have paid for!
Important: After you have purchased any Paid page or Download page and PayPal brought you back to my website, the first thing that you should do is to save that page to your Favorites. Then if something goes wrong you always can come back to re-register yourself on my website again.
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Tags
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