Q about Amana AMH8 2-stage operation

[JarrodS]

Hello,

I've just accepted a proposal to have the AMH80703 2-stage multispeed furnace, paired with the ASX140361 A/C condenser and CAPF3636A6 evaporator coil installed. I have what I believe to be a very fair offer from an authorized dealer that's been a BBB-accredited business for 18 years.

I have a question about the operation of the 2-stages in the furnace. I already have a Honeywell programmable 1-stage tstat that splits the week into Sat, Sun, and MTWTF, splitting each of those slots into four time zones utilizing the "recovery" fuzzy logic feature that learns to request heating or cooling at the right time so that the target temperature is achieved at the appointed program time. Other than missing any potentially new features that we could take advantage of with our new equipment, we are otherwise happy with this existing programmable tstat.

My understanding (mostly from reading here) is that while the AMH8 furnace is a true 2-stage furnace, it is not capable of being commanded to enter low- or high-stage heating by a 2-stage tstat (i.e. you'd have to set such a tstat to operate in single-stage mode and let the logic on the furnace take over). So, is there *any* benefit of spending a couple hundred $$ on the more advanced Honeywell 8000 series that is what my contractor is offering, or should I save my money?

[BaldLoonie]

It times to high from 0 to 16 minutes after a call for heat depending upon what the board thinks it should do. With that system, a old round is all you need. I wouldn't get that furnace.

[JarrodS]

Thanks for confirming what I suspected. My contractor confirms this as well. I'll stick with the current single-stage programmable tstat.

I live in the south. On top of that, this is an upstairs unit. No need to spend megabucks on a fancy furnace for this space - I think it will work out fine and will rarely need to kick into high gear anyway. But downstairs I'm looking at getting a real-deal variable speed 2-stage heating and cooling packaged unit from American Standard. More efficient, since that unit carries most of the load for the house in the winter, and would cruise along on low-cool mode for much of the summer when the upstairs single-stage cooler carries most of the load for the house.

And the unit that was delivered just now is actually labelled AMH80603. I asked about the difference and the distributor said it's the same unit as the 80703. According to him, Amana has recently changed the model numbers to reflect the output BTU instead of the input BTU ratings. That appears to be the case when you look at their latest product spec brochures.

[BaldLoonie]

According to Amana's website, 60 is the input. Sounds like they changed orifices and have reduced the capacity of each model.

[JarrodS]

Yep, you are right. I was actually looking at a 2008 brochure for the 703 model (where it shows the output at around 60). I will be in touch with my contractor about this. Thanks for your help.

[kangaroogod]

I would go with the amvc furnace. If you are in the southern climates the variable speed motor will be well worthy the extra cost. It will give you the ability to do a true 2-stage and will allow future possibilities such as enhanced dehumidification. No brainier for me to go variable.

[JarrodS]

Guys I really appreciate the advice on the variable speed unit - I'm sure it's a better piece of equipment. But it's too late, I already have the multi-speed AMH8 sitting in my attic. It is light-years ahead of the 15 year old Bryant builder-grade unit it is replacing, and even that POS never gave me any issues in terms of heating. The cold pools downstairs in winter, so I'll consider variable down there for maximum comfort in the more challenging space - that's where I spend most of my time anyway.