Honeywell L7224U1002 Guide d'installation télécharger pdf (Page 7)

L7224U OIL AND ELECTRIC BOILER ELECTRONIC AQUASTAT

CONTROLLER

7 69-1720EFS—07

NOTE: Setting the Low Limit above the High Limit

less the High Limit Differential is not allowed

as improper circulator and Zone Control

functions could result.

Anti Short-Cycle Feature

The Anti Short-Cycle feature allows for field selection of a

minimum delay time between burner cycles. Should a call

for heat occur following the end of the previous heat cycle

and before the Anti-Short Cycle delay time is expired, the

circulator will be allowed to run, but the burner will be held

off until the time has elapsed.

NOTE: The Anti Short-Cycle feature is blocked if

DHW demand occurs. DHW demands are ser-

viced immediately, without any delay.

NOTE: When the Aquastat is connected to the oil

primary and/or thermostat via the EnviraCOM

bus, the Anti Short-Cycle time does not apply

to recycle events such as loss of airflow or

flame. It applies only to loss of demand.

ZR-Domestic Hot Water (DHW)

Request

The ZR terminal on the L7224U can be selected to

service an indirect water heater heat request. This

parameter is set via the 3 digit display (see “Adjusting

Settings” on page 5). A heat request via the ZC terminal

will have priority over all other features such as the Anti-

Short Cycle feature or those enabled by the Outdoor

Reset Module (See form 69-2235 for more information).

Frost Protection

The Frost Protection function protects the boiler and

potentially the boiler plumbing from possible damage

which may occur should the water in the system begin to

freeze. The Frost Protection feature is enabled only in the

L7248 (cold start models). The feature default setting is

enabled (ON), but can be disabled using the 3-digit

display. See “Adjusting Settings” on page 5.

When the Boiler temperature drops to the Frost Protection

Limit temperature (fixed 40 °F), the burner is forced on.

The Circulator and ZC outputs remain in the same state

as before the Frost Protection function was enabled.

They can be either ON or OFF during the Frost Protection

cycle.

When the Boiler temperature reaches the Frost Protection

Limit temperature plus a fixed 10 ° F differential, the

burner is turned off unless requested to stay on due to a

different demand.

Thermal Purge Operation

The intent of thermal purge is to insure usable residual

heat in the boiler is circulated until it is sufficiently

depleted from the system before the burner is allowed to

fire. To that end, on a call for heat, the burner is held off

while the circulator runs until the boiler temperature drops

to the thermal purge temperature or a time delay is

exceeded. Both of these parameters are adjustable.

When the boiler temperature reaches the thermal purge

temperature, the burner is allowed to fire. Thermal purge

is only applied when the low limit is set to OFF and will not

interfere with a domestic hot water call for heat or boilers

equipped with Honeywell outdoor reset accessories. For

applications where a Low Limit must be set, thermal

purge is not applied.

In addition to the thermal purge temperature and thermal

purge time delay parameters, two other conditions release

the Aquastat from thermal purge in order to maintain

comfort in the space:

• The boiler temperature has dropped 10 °F from the

beginning of the thermal purge.

• Boiler temperature is cooling at a rate greater than

5 °F/minute while the circulator is running.

The thermal purge feature applies to single zone as well

as multi-zone applications.

Thermal Purge Settings

Some thermal purge parameters are configurable using

the 3 digit display. See “Adjusting Settings” on page 5.

Thermal purge may be disabled by setting the thermal

purge temperature limit to "OFF".

Thermal Purge and Domestic Hot

Water

The thermal purge feature is automatically disabled

whenever there is a call for domestic hot water from the Zr

terminal to ensure hot water is available in a timely

manner. See “ZR-Domestic Hot Water (DHW) Request”

on page 7.

Pump Cycling

The Pump Cycling feature exercises the system pump for

15 seconds after a non-adjustable five day period of no

boiler activity. The Pump Cycling feature default setting is

enabled (ON) but can be disabled (OFF) using the 3-digit

display. See “Adjusting Settings” on page 5.

CHECKOUT

Put the system into operation and observe at least one

complete cycle to make sure that the controller operates

properly. See TROUBLESHOOTING section to use LED

to assist in determining system operation.

Table 4. Thermal Purge Settings.

Parameter name Minimum value Maximum Value Default

Boiler temperature drop Not adjustable Not adjustable 10 °F

Thermal purge temperature limit 120 °F (or OFF) 160 °F 140 °F (L7248)

Thermal purge temperature rate of drop Not adjustable Not adjustable 5 °F/minute

Thermal purge time delay 1 minute 10 minutes 2 minutes

1 2 3 4 5 6 7 8 9 10 11 12 ... 51 52

Commentaires sur ces manuels

Pas de commentaire

Honeywell L7224U1002 Guide d'installation Page 7

Commentaires sur ces manuels