Best Of
Re: Do two wire thermostats short the thermostat wire when they turn on?
Yes you can just add a capacitor at pins 2 & 3, see page 6 and 7 of the App note.
109A_5
Re: Efficiency of an indirect water heater
Not all Heat Losses are equally bad. Some are large and significant. Some are trivial. It is vitally important to know the difference. This is why we need to measure and quantify the heat losses and respect the facts as shown by the data. Otherwise we are chasing down every rabbit-hole.
ModCon Boilers are designed to minimize jacket heat losses. My ModCon Boiler is in a sealed boiler room. The heat losses from my boiler are trivial, especially when running only 8 minutes every 2 hours. My boiler definitely does not "heat my house" in the summer. But the boiler heat losses are included in the boiler thermal efficiency.
I know a plate heat exchanger is good, primarily because of the small size and large surface area - but why do you need one in the first place ? Adding an extra Heat Exchanger just complicates the system, increases the ∆T and reduces efficiency. I prefer to use an Indirect type that does not need an external heat exchange - because it has an internal heat exchanger which will always be more efficient.
My Indirect is a Smart stainless-steel jacketed tank-in-tank type with a very large heat transfer area. It is a very-efficient heat exchanger. This large heat transfer area allows the Boiler to run at a lower ∆T and higher efficiency when making DHW. No external plate heat exchanger required.
Equipment selection and system design make the difference on system efficiency and reliability. This forum should really be discussing "Best Indirect DHW System Design".
Doug_7
Re: PTFE Gasket for #67 LWCO and #14B blow-down valve?
I have placed an order.
EBEBRATT-Ed's anti-seize and fiber gaskets was my next alternative; but it is no surprise that my first choice is to go with what I know.
Thanks for the helpful and insightful comments.
Re: Tower blow down valve needed
You should have a strainer before that valve.
Any motorized valve will work.
Daily makeup water readings should be taken to notice the issue before losing all those chemicals.
pecmsg
Re: Retirement second thoughts
Im in the same boat. It does become harder to stay in the loop when you’re not in the game every day. Mainly putting your hands on the newest and latest stuff.
Sites like this will keep you up to date on the industry, both the newest and the oldest equipment out there gets dragged across HH. It is a unique site in that respect.
Plenty of opportunity for freebie work for neighbors and friends to keep the tools from getting rusty.
Pick a hobby or two. I help out with a local dog rescue group, you get two wins. You and the dog. Also the therapy dog group that my sister is involved with.
The box stores around me are staffed with semi-retirees, many work 4 hour shifts a few days a week. My lumber guy at HD goes in early to restock, leaves at 10:00 AM
You gotta keep the body moving, or lose it.
hot_rod
Re: Do two wire thermostats short the thermostat wire when they turn on?
Hello In_New_England,
I would do it something like this.
Say you want the boiler the run for 10 minutes every 8 hours when the temperature outdoors is less than 32 degrees Fahrenheit. Mostly independent of anything else. (the times are just an example)
If the boiler's normal thermostat has activated then the microcontroller box delays its call by 8 hours (or what ever you want).
The microcontroller would ignore a call from itself (relay closure).
So above 32 degrees Fahrenheit or if the boiler's normal thermostat calls are more frequent than 8 hours the microcontroller will never generate a call for heat.
Fairly simple program for an Arduino or the like.
What is the maximum AC input voltage of the HCPL3700, I could not find it in the data sheet.
The temperature input can be anything you want a temperature switch, Analog or Digital. If you use a sensor that reports the actual temperature to the microcontroller (analog LM34, digital DS18B20, etc.) the frequency of the boiler running can increase as it gets colder outside.
I would probably buffer the relay coil with a transistor and don't forget the diode across the relay coil.
109A_5
Re: Do two wire thermostats short the thermostat wire when they turn on?
HCPL3700
Going by the symbols in the HCPL3700 circuit, D1 and D2 appear to be Schottky Diodes (low forward voltage drop). D3 and D4 seem to be Zener Diodes (Limits the input Voltage). You may not be able to apply 24 VAC directly to pins 1 and 4, you may need (at least) a current limiting resistor. If you use this device I would use the DIP package and install a socket.
Edit: Also look at - Application Note 1004
You will need to filter it too unless your microcontroller's code can deal with the microcontroller's input pin switching on and off at a 120 Hz rate during boiler inactivity.
109A_5
Re: Seeking feedback on new TRV
Re: Seeking feedback on new TRV
I agree, those are beautiful valves. I would've padded the wrench with a bit of cloth when tightening it to prevent scratching. The video is well done but there are a couple of minor errors. At 1:17 Teflon® is spelled as "Tefflon". Perhaps this is a difference between British and American English but at 2:31 and following the heating appliance supplying steam is called a "furnace". Here is the USA a "furnace" is something used to heat air. A "boiler" is used to heat water to steam. I'm not trying to criticize but trying to help you make a better product.
CLamb
