ASHRAE 90.1-2010 Table 7.8 Hot Water Supply Boilers
ASHRAE 90.1-2010 Table 7.8 Hot Water Supply Boilers
(OP)
Looking at the table for hot water supply boilers (for domestic water heating), there is a criteria which indicates >= 10 gal. Part of the requirements is calculating the standby loss.
How can a hot water supply boiler (assuming this means a side arm type) have more than 10 gallons of water in it? I would assume this would make it a storage water heater which is covered in another part of the table and the standby loss calculation matches.
I don't think it is referencing the accompanying storage tank. The energy efficiency of those is covered in another part of the table.
Anybody run into this?
How can a hot water supply boiler (assuming this means a side arm type) have more than 10 gallons of water in it? I would assume this would make it a storage water heater which is covered in another part of the table and the standby loss calculation matches.
I don't think it is referencing the accompanying storage tank. The energy efficiency of those is covered in another part of the table.
Anybody run into this?





RE: ASHRAE 90.1-2010 Table 7.8 Hot Water Supply Boilers
RE: ASHRAE 90.1-2010 Table 7.8 Hot Water Supply Boilers
What is the basis in the ASHRAE Standard for referencing volume as the system volume and not the water heater volume?
Note a of Table 7.8 indicates V is the rated volume in gallons. In the 90.1-2013 User's Manual, all the examples use the water heater volume, not any piping/equipment volume. The loss of heat in the piping system is covered elsewhere.
RE: ASHRAE 90.1-2010 Table 7.8 Hot Water Supply Boilers
RE: ASHRAE 90.1-2010 Table 7.8 Hot Water Supply Boilers
Which question are you referencing?
The original query or the reply to lilliput1?
RE: ASHRAE 90.1-2010 Table 7.8 Hot Water Supply Boilers
I read this as including storage and non-storage type boilers.
The volume requirement would seem to make the requirement relevant to storage type boilers.
Your side arm or non-storage type boiler would then not be required to meet the table's standby losses. However, the storage tank it is feeding would need to have R-12.5 insulation in accordance with this table.
RE: ASHRAE 90.1-2010 Table 7.8 Hot Water Supply Boilers
Both are categories in the chart.
I remember there used to be a designation given to "boiler" as having an input >=200,000 BTUH, but that could be storage water heaters as well.
RE: ASHRAE 90.1-2010 Table 7.8 Hot Water Supply Boilers
The way I see the difference (my interpretation of the definitions) is based on their use. A water heater is used for heating water in a potable hot water system, maxing out around 140°F.
A hot water boiler would be for generating hot water or steam used for some other process. I.E. boiler used to generate steam for a dry cleaning service.
RE: ASHRAE 90.1-2010 Table 7.8 Hot Water Supply Boilers
So, a hot water boiler, in the table would not be for some other process.