Feedback and guidance on a replacement 5 ton HVAC, with AC being most important.


 
7 hours start to finish, 3 guys.

A rather pricey solution, arguably a Cadillac, maybe not a Rolls Royce, solution. "Smart" thermostat, requires Internet access for the advanced functionality (UGH,) new whole house humidifier, etc. Only minor came when they were plumbing in the humidifier, and I found out they were planning on hot side water. Uh...... no, please. This is a tankless water heater. If the flow is low enough, it'll be just like a cold side hookup. OTOH, if the draw is high enough, I'll go broke with that burner cycling endlessly when humidity is called for. Ended up with a cold side hookup, I'll deal with a little more water usage (bet on less than 50 gallons annually.)
 
JKalchik said:
7 hours start to finish, 3 guys.

A rather pricey solution, arguably a Cadillac, maybe not a Rolls Royce, solution. "Smart" thermostat, requires Internet access for the advanced functionality (UGH,) new whole house humidifier, etc. Only minor came when they were plumbing in the humidifier, and I found out they were planning on hot side water. Uh...... no, please. This is a tankless water heater. If the flow is low enough, it'll be just like a cold side hookup. OTOH, if the draw is high enough, I'll go broke with that burner cycling endlessly when humidity is called for. Ended up with a cold side hookup, I'll deal with a little more water usage (bet on less than 50 gallons annually.)
Click to expand...
It does not flow anywhere near enough water to turn on the burner. And even if it did, those burners can throttle down quite low.
 
LMichaels said:
It does not flow anywhere near enough water to turn on the burner. And even if it did, those burners can throttle down quite low.
Click to expand...

Draw on this one is up to 0.7 gals/min. I have observed this heater kick on with a pretty low draw. In all honesty..... a few gallons of water annually is a pittance compared to cycling that heater.

One other thing to note is that these gents really did a nice job of packaging this installation up. Just replacing the AC evaporator coil would have been a PITA, as the only easy access is from the front. Left side is the return plenum, right side is just enough space for combustion ducting, and the rear is blocked by the hose septic drain.

Right now, it's 77 F, about 78% RH outside, and 75 inside and about 50% RH. System has been running for a couple of hours and I have a good first shot at a schedule. It's also far quieter than the old system.
 
Last edited:
DanHoo said:
View attachment 96589View attachment 96590View attachment 96591
Click to expand...
must be inexpensive to run and you have solar too. curious how your daily costs come in.

i am digging the new home with solar. my electric bill is puny compared to the old home and my inside temps are quite nice now too.

and we installed smart shades this weekend. they're programmed to close at 1PM on the southwest side of the home so as to avoid heating up the house. and they open at sunset so we can see the sun go down once the intense heat is beyond us. and then we get the nighttime lights show.

modern home technology has really advanced over the past few years.

enjoy your new cool home!!!
 
Our water heater has the same flow (.7 GPM). Which at times is hard to live with. With the goofy govt. mandated low flow faucets. So, it makes it so hard to do simple functions like get a "lukewarm" flow out of a faucet. So bad on the kitchen sink and my shower, I found the restrictors and tore them out. Low flow faucets undo all the good a tankless heater provides.
Then you get the horrible "cold slug".
Right now outside relatively cool but muggy. So a cool function it has thanks to the advanced features allow it run at very low output and dehumidify the house but not over cool it. So I think you're really gonna like many of those features
 
LMichaels said:
Our water heater has the same flow (.7 GPM). Which at times is hard to live with. With the goofy govt. mandated low flow faucets. So, it makes it so hard to do simple functions like get a "lukewarm" flow out of a faucet. So bad on the kitchen sink and my shower, I found the restrictors and tore them out. Low flow faucets undo all the good a tankless heater provides.
Then you get the horrible "cold slug".
Right now outside relatively cool but muggy. So a cool function it has thanks to the advanced features allow it run at very low output and dehumidify the house but not over cool it. So I think you're really gonna like many of those features
Click to expand...
Oh, wait a sec..... I think I see where our disconnect is.

The HUMIDIFIER will draw up to 0.7 gals/min. The water heater, a 199k BTU Rheem Commercial, will flow far more than that, and I think will trigger well below that. I don't like the idea of a high speed cycle on the heater, and I don't want to burn gas just for the humidifier. So, a cold draw it is, and a few extra gallons per year. Yeah, I know, the heater should be able to throttle itself, but I just don't see the advantage in this situation.

Yes, the delivery curve is a little different coming from a tankless heater compared to an insulated tank. Yes, the temp varies a bit under low draw usage, but don't really get the "cold slug" you're referring to. For example, when I do start the shower, as soon as I get hot water, the temp stabilizes within a few seconds, even with a restrictor head.
 
When I had the new shower installed they installed one of these REALLY low flow systems. Royal PIA. Not 100% but it would only flow about 1.5 gpm. Yeah the heater would turn on but was very unstable. Another issue is the very long run from the heater to my kitchen sink. When the basement is cold (i.e. winter), when you want hot water the kit sink faucet was another of those stupid restricted designs. So, it took forever plus a week of Sundays to get hot water to the sink. Royal PIA. Talked to the folks at Richmond tech people said pull the restrictors out. While the water may flow SLIGHTLY above the threshold, they said it's not a high enough flow rate to get the unit to stabilize. So I removed the restrictors and voila good solid flow and temps. Where the trouble comes in, is the new bathroom sink faucets. Somehow they've built the restrictions into the faucet. So, they're extremely low flow and if you try to run say "lukewarm" water rather than all cold or all hot, you can only do so for a very short time before the cold slug comes because the water heater went below threshold and shut off.
Understand too, I have a much older heater (I installed it in 2005). I think the valves in the newer ones are better, plus the new ones have a circulate feature which I think helps as well.
But I'm not replacing the unit just because of that.
I am actually thinking of making a "hybrid" system. Getting a small 20 gal or less tank unit, and having the tankless feed into it. Which is basically what a lot of new systems are doing. I think it will give me best of everything :D
 
[ArteJohnson]Veddy interestink.[/ArteJohnson]

Final walkthrough this afternoon and paid it off. The contractor recently got wind of an unadvertised program from our electrical supplier that's a result of the high efficiency heat pump install, says it should cut our electrical rates in half.
 
LMichaels said:
I think the valves in the newer ones are better, plus the new ones have a circulate feature which I think helps as well.
But I'm not replacing the unit just because of that.
I am actually thinking of making a "hybrid" system. Getting a small 20 gal or less tank unit, and having the tankless feed into it. Which is basically what a lot of new systems are doing. I think it will give me best of everything
Click to expand...

Yeah. I am pretty sure that ours is far more responsive and controllable than yours is. I had talked Dad & my brother into a point of use instant heater when they built the new sprayer building 20+ years ago, and my brother's always said that it's either cold or scorching. He's just unplugged it (all electric) and is washing his hands now in 45-50 degree water.

Tiny little reserve tank...In your case, I can see the attraction. I don't think that it would do much for our case.
 
JKalchik said:
Yeah. I am pretty sure that ours is far more responsive and controllable than yours is. I had talked Dad & my brother into a point of use instant heater when they built the new sprayer building 20+ years ago, and my brother's always said that it's either cold or scorching. He's just unplugged it (all electric) and is washing his hands now in 45-50 degree water.

Tiny little reserve tank...In your case, I can see the attraction. I don't think that it would do much for our case.
Click to expand...
Yeah, I honestly think it would work but I'm leaning more toward simply replacing the unit with a new one may be the best bet. I keep wondering "How long can thing last?" It's nearly 20 years old. Other than the recall on the main PCB has never needed service.
 
LMichaels said:
Yeah, I honestly think it would work but I'm leaning more toward simply replacing the unit with a new one may be the best bet. I keep wondering "How long can thing last?" It's nearly 20 years old. Other than the recall on the main PCB has never needed service.
Click to expand...
Gotta wonder about what changes would be required in ducting. Both the tankless heater and the new furnace both have 3" PVC inlet and outlet ducting. The new furnace ducting goes right up the old chimney, no new holes in the house. I would suspect (and hope) that a new tankless would give you better service than the old tankless and a reserve tank.
 
JKalchik said:
Gotta wonder about what changes would be required in ducting. Both the tankless heater and the new furnace both have 3" PVC inlet and outlet ducting. The new furnace ducting goes right up the old chimney, no new holes in the house. I would suspect (and hope) that a new tankless would give you better service than the old tankless and a reserve tank.
Click to expand...
Well, the old exhaust duct for my old tank unit is still there. Because when I had the roof don't I hadn't yet contracted for the furnace (did not have the $$$$). I wish I'd don't both so I could have had the roof closed up just like the way I showed you on my fireplace (no more chimney) thank to the new gas one. I would love to have had the roof closed up around that old exhaust. Anyway it's all capped downstairs.
It would not be hard for me to re-vent a new tankless. The new ones are PVC vented. Which I don't think would be an issue since my current one is all gasketed 304SS vented. PVC would just be an unnecessary "convenience".
I'm just at the point of having a 19 yo device that only has an avg life span of 7-10 years and wondering when I might have a catastrophe :D
 
LMichaels said:
When I had the new shower installed they installed one of these REALLY low flow systems. Royal PIA. Not 100% but it would only flow about 1.5 gpm. Yeah the heater would turn on but was very unstable. Another issue is the very long run from the heater to my kitchen sink. When the basement is cold (i.e. winter), when you want hot water the kit sink faucet was another of those stupid restricted designs. So, it took forever plus a week of Sundays to get hot water to the sink. Royal PIA. Talked to the folks at Richmond tech people said pull the restrictors out. While the water may flow SLIGHTLY above the threshold, they said it's not a high enough flow rate to get the unit to stabilize. So I removed the restrictors and voila good solid flow and temps. Where the trouble comes in, is the new bathroom sink faucets. Somehow they've built the restrictions into the faucet. So, they're extremely low flow and if you try to run say "lukewarm" water rather than all cold or all hot, you can only do so for a very short time before the cold slug comes because the water heater went below threshold and shut off.
Understand too, I have a much older heater (I installed it in 2005). I think the valves in the newer ones are better, plus the new ones have a circulate feature which I think helps as well.
But I'm not replacing the unit just because of that.
I am actually thinking of making a "hybrid" system. Getting a small 20 gal or less tank unit, and having the tankless feed into it. Which is basically what a lot of new systems are doing. I think it will give me best of everything :D
Click to expand...
Are your pipes clogged feeding the faucets?
If so, I have an ingenious way to fix those.
 
Tony Coloma said:
Are your pipes clogged feeding the faucets?
If so, I have an ingenious way to fix those.
Click to expand...
Nope everything is either copper or pex in my house. And I use a softener so there is no accumulation anywhere in my system. It's just the vagaries of older tankless water heaters. The new ones have much more tightly controlled flow sensors.
 
Bob Bailey said:
I'm with @Brett-EDH on only replacing the AC unit. Unless you're having problems with the furnace, leaving it alone will save you a chunk of change. Just had our AC system replaced and saved about 2.5K by leaving the furnace alone. Even if it needs to be replaced later, there isn't much redundant labor involved, since it sits on top of the evaporator unit.

As @LMichaels says, there aren't that many actual manufacturers of central AC systems. Kind of like household appliances, many times the only difference from one brand to another is the badge.

Just stick with a major brand and you should be fine. Carrier, Trane and Lennox come to mind. Our new system is Lennox and very quiet. The contractor is what you need to be careful about selecting.
Click to expand...
Looks like I got bit in the behind by not replacing the furnace along with the AC unit. The blower went out yesterday when the temp. was over 100. Even if parts are still available, thinking about just replacing the unit to be safe.
 
Bob Bailey said:
Looks like I got bit in the behind by not replacing the furnace along with the AC unit. The blower went out yesterday when the temp. was over 100. Even if parts are still available, thinking about just replacing the unit to be safe.
Click to expand...
That should be a simple small motor. Might be a tad difficult to get to with corroded fasteners, but a new motor isn't all that expensive. That's one of those parts that I would look at replacing long and hard before replacing the furnace. Shoot, it might actually be as simple as a failed capacitor.
 
You must log in or register to reply here.

 

Back
Top