T475A1057

BillW@honeywell

I will pass this on to the market guys, it's a good idea. Thanks for the feedback.

[Deleted User]

T475A1057

Does anyone have and can post the temperature curve chart for a Honeywell T475A1057 outdoor reset control? I want to try the outdoor reset control on my boiler but need to know the where to set the proper setpoint. Did heat loss calculation and boiler is 20,000 btu oversized. (Thinking of removing and plugging 1 of 4 burner tubes but want to try the reset control first, boiler is 80,000 btu output...
only need 60,000).

bob_25

1to1.5

Mike, the ratio of the control you have is fixed at 1to 1.5 . For every degree the outside temp drops the system temp will increase 1.5F . To figure out set point you need to know system design water temp and outdoor design conditions.
Example; 70* inside when it's -10* outside and system design calls for 200* water. 70-(-10)=80 , 80times1.5(reset ratio)=120 , 200-120= 80 which is the set point. The T475A also has an adjustable differential from 6 to 20 degrees, your choice. bob

BillW@honeywell

Thanks for thinking of us, but here's a better idea...

> Does anyone have and can post the temperature

> curve chart for a Honeywell T475A1057 outdoor

> reset control? I want to try the outdoor reset

> control on my boiler but need to know the where

> to set the proper setpoint. Did heat loss

> calculation and boiler is 20,000 btu oversized.

> (Thinking of removing and plugging 1 of 4 burner

> tubes but want to try the reset control first,

> boiler is 80,000 btu output... only need

> 60,000).

BillW@honeywell

Here's another control that is closer to what you want...

The T475 is an older design, and it will work as was described above. The newer control is the AQ475A1004, which will give you reset capability, domestic hot water priority, warm weather shutdown and other goodies. The two sensors needed are included. Go to http://hbctechlit.honeywell.com and type in AQ475A to download a complete tech sheet. Available from any Hydronic oriented Honeywell distributor.

[Deleted User]

new control

Thanks Bill and Bob for your input and advice. I hooked-up the T475 and it is doing well so far, but, I will check with the guys at the supply house to see what an AQ475A will set me back and see if the price is worth the fuel savings. (Have 4 zones of baseboard and will need the R8889 also). Might be over-kill for my needs as I don't need the DHW loop function.
Thanks Again

[Deleted User]

Don't aways

agree w/ Bill. However, the AQ475 will probably pay for itself 1st year. The problem w/ the 1950's T475 is that there is practically no way to hit the temperature mark. Either too hot, or too cold. Fixed reset ratios do that. And. Higher than 70 degree ambient temperatures @ the case will require raising the settings in cold weather, which results in overheating in milder weather.

The AQ allows you to dial in what you need for all weather. Now, if only it had a set of contacts for a temperature setback timer. Like the _ _ _ _ _ _.

Are you listening, Bill?