Where To Get Parts & Tools for Hacking Heat Pumps

[AC_Hacker]

Originally Posted by MN Renovator

Nothing established as far as plans go but I'm really thinking about DIY'ing in an R410 condenser plus coil if I can get something above minimum SEER.

Could you explain this project in a little more detail?

-AC_Hacker

[MN Renovator]

Originally Posted by AC_Hacker

Could you explain this project in a little more detail?

-AC_Hacker

I'm not sure how much detail you are looking for. If I find a used system on Craigslist that is 14 SEER or better and either 1.5 ton or 2 ton and is a really good deal, I'm looking to replace my old 8 SEER 2 ton Janitrol. I'm not sure what kind of details you are looking for, I'd buy the tools that I would need to run the lineset and I'd sweat the lines, install a new in-line drier, vac the system, and charge it. If I'm lucky and it was a pumpdown, I'd release the gas into the lines and hope it was enough and maybe get a pro to adjust it if needed. There isn't too much different between a mini-split and a full size unit other than it being a bit harder to get the coil into the supply plenum(it needs to be appropriately sized), running the drain line, and dealing with a heavier unit and a more difficult lineset. If I can't find either a good price or a higher SEER unit, I'll go with one of the best mini-splits on the market either Mitsubishi or Fujitsu as they have the highest performers.

[AC_Hacker]

NOTE: I am duplicating this post I made elsewhere because it is perfectly appropriate to this thread.

-AC_Hacker

Originally Posted by launboy

Not everyone's got the ambition to tackle it themselves.

You aren't gonna believe what I just bought off of Craigs List...

I just got an ASHP that heats water! It is a unit that is meant to be plumbed into a hot water heater. It is a 12,000 BTU unit that has no tank. You supply the tank. In the event that the ASHP can't supply the amount of heat (because the air temp is too low), it turns the function of making hot water over to resistance heat.

The guy I bought it from paid $1,400 for it new, and he tried to use it to do hydronic heating... only thing is he followed the 'normal' rules of thumb for a hydronic (wide PEX spacings, staple up, etc.) system that is going to use fossil fuel and can supply feed temperatures in the range of 160F. He did staple up, spreader plates, etc. Trouble is his heat pump can only supply water up to 125F. So his system never kept the house warm and comfortable.

So, long story short, the unit is a couple of years old, and I got it for $400.

And I have been insulating my house and researching floor configurations and testing computer models for feed temperatures in the range of 95F... This thing can happen!

-AC_Hacker

[Geo NR Gee]

Great score. You got me thinking of a hydronic system now too. If my feet are warm, the rest seems to follow.

Was this under "HVAC" on Craigslist?

[AC_Hacker]

Originally Posted by Geo NR Gee

Great score. You got me thinking of a hydronic system now too. If my feet are warm, the rest seems to follow.

Was this under "HVAC" on Craigslist?

Yeah, hydronic heating is well known for being really comfortable. But you need to do your homework before you begin...

I got it in the "For Sale" section. I searched for "heat pump".

-AC_Hacker

[AC_Hacker]

Harbor Freight is currently running a special on a manifold gauge set:

It's a pretty good price for a pretty good gauge set, with a built in sight glass.

It seems to be primarily set up for R-134a, R-404a and R-407c. It will read into the range that is appropriate for R-22 and R-290, too. There are scales on the gauge to help with super heat and sub cool calculations for R-134a, R-404a and R-407c, but many HVAC people never use these scales and prefer to work with paper PT charts and accurate thermometers. In some cases, spreadsheets containing formulas to generate the PT charts have replaced paper PT charts.

The connector ends on gauge sets are not all uniform. 1/4" flare is referred to as 'standard'. There is a unique fitting for R-134a, also a unique fitting for R-410a. Adapters to go from 1/4" flare to R-134a and from 1/4" flare to R-410a are easily available. The HF gauge set has 'standard' ends with R-134a adapters.

Ebay usually has a pretty good selection of manifold gauges at attractive prices.

R-290 Gauge sets (that have R-290 scales on the gauge face) are also available, usually at higher cost.

Don't forget junk shops and pawn shops. Know your prices before shopping in a pawn shop.

-AC_Hacker

[MN Renovator]

I have a manifold gauge set that is likely 3 decades old or older. R-12 R-22 and R-502. I need to get an idea of how to use these, soon enough I might end up swapping out my R-22 unit for something more efficient or less broken(if I need to ever replace my A/C or furnace due to a failure). A question like this comes up: How are you supposed to purge the lines to avoid getting the humidity into the system. I'll have to snag a good book on this. ...or rather my buddy who is taking an HVAC course, he'll have the books and the brain. I'd love to browse through the ACCA manuals especially considering the only copy of the Manual J in my counties library system appears to be stolen or otherwise out of placed even though it is marked as checked in. Books are tools, yeah?

[AC_Hacker]

Originally Posted by MN Renovator

How are you supposed to purge the lines to avoid getting the humidity into the system. I'll have to snag a good book on this. ...or rather my buddy who is taking an HVAC course, he'll have the books and the brain.

Basically, you need a vacuum pump and some purging gas (dry nitrogen is usually used).

If you have a buddy in the trade, he would be your best resource.

Grab a 12-pack of his favorite beer, and give him a visit.

-AC

[MN Renovator]

Wow, seems like lots of work if they need to purge the gauges every time they use them. I keep reading about techs checking pressure on their 'tune up' visits and I thought they slipped over that step and just connected the gaugeset and checked the pressure. Good info, I might skip having a tech do anything other than cleaning my evap coil if everything else seems fine.

[AC_Hacker]

Originally Posted by MN Renovator

Wow, seems like lots of work if they need to purge the gauges every time they use them.

I think I misunderstood what you were asking.

The amount of air in the gauge lines is very small, compared to a typical system volume, so a rare and occasional checking of the system pressure wouldn't have an appreciable effect.

But it's a little like an x-ray, if you do it too often, the risk increases.

Modern HVAC systems are 'hermetically' sealed, so if the brazed joints are good, there will be no leaking. All of the mechanical seals are inside of the hermetic boundary.

A properly set up GSHP should be good for two or three decades with no repair, other than water pumps, and control electronics that are external to the vapor compression system.

ASHPs are left out in the weather and are subject to large temperature and humidity swings so their lifespan is maybe 10 or 15 years.

There is mechanical wear, and eventually the system will need to be replaced, but it's not like a car engine, which is not hermetically sealed and requires regular periodic checking of vital fluids.

If you have a HVAC tech who is regularly coming around checking refrigerant levels, it's less a matter of system maintenance, and more an issue of job security.

-AC_Hacker