Crown Mega-Stor 2 Installation Manual

Residential Applications

Table A.1 shows the minimum sized indirect water heater (IWH) that should be considered for one and two family homes based

onthenumbersofbedroomsandbathroomsbeingserved.Incaseswheretheboilerissizedsignicantlylargerthanthatshown

in column (e) in order to meet space heating demand, there is usually no need to add boiler capacity just for the IWH. Note that

the sizing recommendations shown in Table A.1 may not provide satisfactory performance when there are unusually high peak de-

mands,suchaswhenmultipleshowersareusedsimultaneouslyorwhenahottubislled.Toaddressthesecases,reviewTables

A.2andA.3andmakeadjustmentstoIWHmodeland/orboilersize,tomakesurethatthepeakdemandcanbesatised.Forhot

tubs, it is recommended that the IWH model have a domestic water volume at least as large as the nominal volume of the tub.

Commercial Applications

Useaxturecountmethodtodeterminethedomestichotwaterdemand,suchasthatshownintheServiceWaterHeatingchap-

ter of the ASHRAE Applications Handbook. Then use the data provided in Tables 2.1, A.2, and A.3 to select the boiler and IWH.

Table A.1: Indirect Water Heater Sizing for Typical One and Two Family Units

(a) (b) (c) (d) (e)

Number of

Bathrooms

Number

of Bed-

rooms

Model

First Hour

Requirement

(GPH)

Min. Boiler Output

(MBH)

1 to 1 1/2

1 MS2-030 43 27

2 MS2-040 60 36

3 MS2-040 60 36

2 to 2 1/2

2 MS2-040 60 36

3 MS2-040 70 36

4 MS2-040 72 38

5 MS2-050 90 50

3 to 3 1/2

3 MS2-050 72 50

4 MS2-050 82 50

5 MS2-050 90 50

6 MS2-050 92 50

APPENDIX A. SIZING

NOTICE

The following procedures are used to size indirect water heaters based on the amount of hot water

which will be required during a given hour. In doing so it is assumed that this demand will be evenly

spread out over the course of the entire hour.

THESE SIZING PROCEDURES ARE PROVIDED AS A GUIDE TO ASSIST THE PROFESSIONAL

INSTALLER IN SIZING INDIRECT WATER HEATERS. BECAUSE OF THE LARGE VARIETY OF DEMAND

SITUATIONS ENCOUNTERED IN THE FIELD, THE SUITABILITY OF THESE PROCEDURES TO ALL

INSTALLATIONS CANNOT BE GUARANTEED.