Trane XV90 cfm question

JohnH1 · 04-13-2009, 10:21 PM

Now here is where it gets a little tricky.
First the background: I currently have my cooling set to run at 80% of the dip switch setting speed which is currently 80% of 400 CFM/ton or 320 CFM/ton. I have a 4-ton so I get 1280 CFM. According to my static pressure readings when I run in fan-only I get 50% of my cooling speed or 640 CFM, which is what I would expect since my service facts documents states that the fan is set up to run at 50% of the cooling speed. Now here is the interesting part. The green light blinks 8 solid times suggesting 800CFM (not 640CFM like I expected). My question is, is the green light reacting to my dip switch settings or does it actually monitor actual airflow?

Key1[/quote]

The only avalable settings are 350 / 400 or 450 cfm per ton. You may be reffering to the comfort R setting Re: the 80% air flow.Or do you have a humidistat that drops the blower 20% durring high humidity situations. If you are a 4 ton system at 400 cfm per ton 50% of that is the 800 cfm you are running. Sounds like it is operating ok.

**beenthere** · 04-13-2009, 10:27 PM

What jumper are you uing to get 80% air flow in fan only?

key1cc · 04-14-2009, 09:28 AM

Quote:

Originally Posted by beenthere

What jumper are you uing to get 80% air flow in fan only?

I don't have my log book at work so I am am going by memory but prior to cutting the BK jumper my static was ~1.1 cooling and ~0.53 on the "fan-only" setting....which is 50% of cooling (Dips were set at 400 CFM/ton). After I cut the BK jumper my static dropped on cooling to ~0.77 as expected since the airflow is 80% . Also my static dropped on "fan-only" to ~0.38 (from 0.53) which I beleive is 50% of the 80% (or 40%).

If I want the "fan-only" to run at 80% (same as cooling) I simply jumper Y-G.

Key

**beenthere** · 04-14-2009, 12:00 PM

Ok.

I thought you were talking aout a dip switch jumper I didn't know about.

key1cc · 04-14-2009, 12:31 PM

Quote:

Originally Posted by JohnH1

The only avalable settings are 350 / 400 or 450 cfm per ton.

Actually there are more settings for those in the know

See the attached Trane Pocket guide.

Key1

**beenthere** · 04-14-2009, 02:01 PM

I have that guide, and the other one, or back side of it.

Somewhere.

JohnH1 · 04-14-2009, 11:03 PM

If you are trying to better controll the constant air flow. I use the TCONT402 with my XV90. It has a BK termonal that you can choose anywere from 35% to 100% air flow.

key1cc · 04-15-2009, 07:49 AM

Quote:

Originally Posted by JohnH1

If you are trying to better controll the constant air flow. I use the TCONT402 with my XV90. It has a BK termonal that you can choose anywere from 35% to 100% air flow.

I know......I only found out they existed after I purchased the TCONT803. Also, the 402 is non-programable....not sure why they took the "35-100% airflow" flexibilty out of the supposedly higher scale programable versions like the 803.

Key

WhatWasThat? · 04-26-2009, 02:09 AM

Quote:

Originally Posted by key1cc

Of course I confirmed the airflow change by measuring static pressure with the Dwyer (Best Hvac tool a DIY'er could have in my opinion

).

Key1

I think I need to get one of those ... (& this scares me to ask this $$) how much do these cost?
Whew! I made it. Glad it's DIY.

I've read some of your HVAC threads. In fact we've conversed

.

**beenthere** · 04-26-2009, 07:43 AM

Quote:

Originally Posted by key1cc

I know......I only found out they existed after I purchased the TCONT803. Also, the 402 is non-programable....not sure why they took the "35-100% airflow" flexibilty out of the supposedly higher scale programable versions like the 803.

Key

Probably a cost issue.

key1cc · 04-26-2009, 10:20 AM

Quote:

Originally Posted by WhatWasThat?

I think I need to get one of those ... (& this scares me to ask this $$) how much do these cost?
Whew! I made it. Glad it's DIY.

I've read some of your HVAC threads. In fact we've conversed

.

I guess you have a different identity on HVAC-Talk.

Quite a few people like to have a different identiy for some reason. Not me and BT though

.
Here is the link to amazon. When I purchased it it was $60 bucks....price has gone up to $78 through Amazon (I suspect you can find it cheaper elsewhere).
http://www.amazon.com/Dwyer-1-0-Wc-M...755113&sr=8-14

Don't forget the Static pressure tip....you will need that also.

Here is the link for the A303 tip
http://www.amazon.com/s/ref=nb_ss_hi...+tip&x=15&y=24

Key1

**beenthere** · 04-26-2009, 10:30 AM

If he lives in MD, I think I know who he is on the other site.

I think I edited a few of his post.

key1cc · 04-26-2009, 11:44 AM

Hey, BT
on another note. Do you know of any issues with me using pvc for my fresh air intake instead of metal duct? no one is answering me (so far) on the other site...

**beenthere** · 04-26-2009, 12:03 PM

Only question would be if it is large enough for the air volume you need.

And you might have a hard time finding a damper set up for it.

PVC is used as an under ground duct(and on some high velocity systems), so no harm in using it.

key1cc · 04-26-2009, 01:02 PM

Quote:

Originally Posted by beenthere

Only question would be if it is large enough for the air volume you need.

And you might have a hard time finding a damper set up for it.

PVC is used as an under ground duct(and on some high velocity systems), so no harm in using it.

Thanks for the feedback.
I could use a 6 to 4 inch reducer and connect 6 inch metal duct to 4 inch pvc inside the house and put the damper in the 6 inch metal. My concern is that 4 inches might not be quite enough since according to my ductuputer it will flow less than 1/2 the air of 6 inch duct at my static pressures..
I have been unsuccessful finding suitble outdoor 6 inch pipe.....
Key1