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So while setting up new equipment (setting gas pressure after converting to LP) and using my combustion analyzer, the pressure starts low, say 7" wc but im getting high(ish) CO. I assume increasing...

I have a builder wanting us to install Mitsubishi MLZ one way ceiling cassettes in several high end semi-custom homes he is building. I haven't installed Mitsubishi but i have done ceiling cassettes....

Hmm...that might be a better solution for most situations right there. Install a supplemental mini split in a living room or master bedroom or wherever the occupants would be most likely to stay once...

I would imagine you want to size the ducting to work with the full capacity of the system but match the low stage to the actual need of the house. I've heard varying opinions on "oversizing" ducting...

I was hoping someone could direct me to some studies/tests done on the energy usage of different sized systems for the same load. I have never taken any classes on load calc or system design or...

As in with something like rx11? It seems to me half the people you ask say its a waste of money and and just contaminates the system further while the other half say you should always use it. My...

I am wondering what some best practices are for determining if too much oil was left in a system from a bad compressor and how to deal with it. If oil is in an evap coil it seems unrealistic to...

And he is their head service tech according to the podcasts

Good stuff, thanks for the input everyone. I will give him some options

I have a friend that works for a utility company and he asked me if i can set up a heater that kicks on when power goes out at some of the more remote buildings. I know almost nothing about the size...

I missed this somehow, thanks.



That is crazy, i would think that would take 100 years. I just found a 7 year old unit that was converted to propane when installed but the orifices for the next...

Im about as far from an expert on this as you can get, so im here to learn. Would the outside air temp that is being pulled in for combustion air not have a significant effect on stack temp?

Really? I thought you had to go with POE oil with almost all the R22 replacements.

If it is a home owner with an old system i like to give them the option to recharge an r22 system because i've...

Any good youtube channels that show how to make sheet metal like that? I can make decent caps and pans and that's about it, haha. I wouldn't even know where to begin with calculations either...

I'm told it can range from about 900 BTUs/cu.ft. to about 1100

It looks like 1025 is normal for this area according to these links. It would probably depend on who you ask if you can just install...

I cannot find any info through internet searches or utility company website (possibly user error) about the heat content of natural gas to areas in northern california. PG&E does most of the areas we...

Honestly, you are probably right, but it's hard not to take it personally, especially since my father-in-law runs it and i intend to take it over. I am trying to modernize the company one step at a...

Good to know. One question for Bill, the measure quick app has an option to scan a QR code for a Bacharach combustion analyzer, so i assume they (or certain ones) work with the app? Perhaps i will...

Ah, yes. The obligatory insult of my company after being honest on an hvac forum. Always a good time.

By entry level i mean the cheaper ones. Testo, for example has analyzers that range from...

I have never used a combustion analyzer before and have started learning a bit about them. I would pretty much have to self train with the help of youtube and podcasts. It would be really helpful if...

Nevermind, i found it. There's a screen at the check valve that is very clogged. Now i have a check valve that is taken apart....

I am working on a Trane WD150 and looking for a restriction. I've already spent way too much time on this thing and can't find it so maybe there is a filter inside the copper lines somewhere that is...

The refrigerant was pumped into the condenser so i was only pulling a vacuum on the lineset and evap coil

Is there a way to prevent this? I did not flush the system out because it wasn't a repair, i was just moving the furnace and evap coil. Just blast it out really good with nitrogen?

Oil is fresh. The pump can pull down to 40-50 microns with the gauge hooked directly to it. I also thought maybe refrigerant was getting pulled out and causing the gauge to read low at times but i...

I am fairly certain that my micron gauge, testo 552, is malfunctioning. As the vacuum is running it reads a steady drop (much slower than i feel it should be) but slows down a lot at about 2000...

If only it was a recovery machine also....

WTF is this all about?

I have most of the testo stuff and i am trying to get better with the MeasureQuick app since they work well with it.

There are 2 things about Testo probes that drive me crazy: the air...

Yes

The filter dryer was replaced and a vacuum was pulled to below 500 microns. We recovered the original r22, so if excessive oil is the issue then i guess thats not enough to get all the oil out. We...

I put the new make shift fan shroud on and it helped some but the pressures still fluctuate. I added some refrigerant and it didn't help much. Low side bounces between low 40s and upper 60s. High...

When i was there the fan was going but no voltage at Y, i didn't have time to go check inside. This is at a subway restaurant in big shopping center.

I'm going back there this morning with some...

Short version: how can a unit with no txv have the same symptoms as a hunting txv? (Pressures fluctuating up and down)

More details: this is a 12 year old package unit that our newest tech has...

So the level of crud scrubbed off by poe is typically not going to be more than the filter dryers can handle? That is good news to me.

The one that i flushed out where tons of black oil came out...

So since all compressors (that i use) are now POE oil and i have read that POE will basically scrub off a lot of what mineral oil could have left on the walls or the refrigerant system, it would seem...

I've noticed the newer (I'm guessing because of efficiency) the unit, the more "undersized" a compressor will be. I recently installed a 16 SEER 5-ton system for my brother and the compressor is 44k...

Definitely sounds like a restriction. In what way did the old compressor go bad?

Does it specifically call for a 3 ton furnace for airflow purposes? Is it a high humidity area where you need more latent removal/dehimidifying? Or is it sizing it for heater BTUs?

Honestly, i've...

I purchased a kit from truetechtools.com with core removal tools, 1/2" hoses and a tee to pull from both sides. It took me about 45 seconds to pull down to 300 microns on a new 2.5 ton i installed

My core removal tools that i use during evac have valves, which i always shut before turning off the vacuum

Great info, thanks guys

I attempted to blow out the lines with nitrogen and rx11, which ive only used a couple times and im not convinced it works very well. Or im doing it wrong.

I have a set that i bought from true...

Does pulling a vacuum after a compressor replacement not pull out oil from the compressor? I am pretty new to pulling a vacuum and am trying to learn the ins and outs of it. I replaced a compressor...

Its a free app so i can't complain too much. I have to think it uses some well thought out engineering formulas

A 6" hose might not hold much and you might be able to have the a very short period of time that the core is depressed and you hose isn't quite making seal, but this holds less and that time is...

I recently heard about the MeasureQuick app and have been trying to use it because i feel like it can be a great training and testing tool. I've entered all the data into the app for only a handful...

So if you were to install a larger evap coil would it be typical to change out the metering device to match the condenser?

Do these rules still apply to TXVs?

So a friend asks you to look at their a/c, you go over there and say "sorry, i dont work on systems that aren't AHRI matched"?

I am asking for help understand a general principal because it...

I haven't run into many mismatched coils but I replaced a condenser for a friend with a 5-ton evap (with a piston) and a new 4-ton condenser. After reading some posts from a while back it seems...