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Types of combo systems--Model all tankless systems as a boiler and a…
Types of combo systems--Model all tankless systems as a boiler and a domestic hot water heater
storage tank water heater combo system (condensing and non condensing)
select "combo heating/DHW"
Click on combo heating /dhw tab
Select Energy Source, then Equipment type
Under output capacity select Calculated
Do not change Efficiency defaults
use default flue diameter
Make and model when efficiency is known
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Condensing systems
CONDENSING tankless water heater combo system, with secondary
Select boiler, and energy source, gas or propane only. Under output capacity select Calculated, do not
change
eff or units, use default flue diameter, Make and model if default values not known.If EF is more than.9, select "condensing"
Go to DHW section, use same energy source as boiler unless it's a solar system
Tank type, use instantaneous (condensing)
make a new h2k file, click Combo Heating DHW, use same energy source as boiler, select the most appropriate eqpt type, select appropriate volume, and note the default EF.
Go back and give the instantaneous tank from original the user specified EF from the temp H2k. Use 0 for flue diameter. Put in the manufacturers field the EF.
tankless water heater combo system, no secondary, CONDENSING
Select boiler and fuel type, gas or propane only. If EF is = to or more than 90 select condensing. If less than .9 select Induced draft boiler
Use Calculated for output capacity. and use flue diameter default value. Input make and model if default values won't be used
In tree, go to DHW , use same energy source as boiler.
Tank type, use Instantaneous (condensing)
Fill in EF with User Specified, or default if not known.
Fill in tank location and 0 for flue
Use workaround in info
Non Condensing
NON CONDENSING tankless water heater combo systems, with secondary
Select Boiler
Select Fuel source (gas or propane only) and Eqpt type. if EF less than .9 select most appropriate type with no pilot
Under output capacity select Calculated, do not change eff or units, use default flue diameter, Make and model if default values not known
Go to DHW section, use same energy source as boiler unless it's a solar system
Tank type, use instantaneous
To find the EF, Start a new house file, use the COMBO heat DWH, usually select "Heater with induced draft fan" enter correct tank volume, then get the EF that is defaulted from H2k temp file.
Enter that EF, use 0 for flue as you already put that in with the boiler
type in 'workaround" in info field
So what you're doing here is modelling a boiler with an instantaneous DHW system. The difference here is that you're using H2k to come up with an estimated EF for the TANKED system
tankless water heater combo system, no secondary, Non Condensing
Non Condensing tankless combo with no storage tank
Under type 1 heating, select Boiler
Select fuel source gas or propane only, and eqpt type. If it has an EF of less than .9 use induced draft boiler, no pilot
Under output capacity select Calculated, do not change eff or units, use default flue diameter, Make and model if default values not known
Go to DHW section, use same energy source as boiler unless it's a solar system
Tank type, use instantaneous
Enter EF, if known, otherwise use defaults
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So what you're doing here is modelling a boiler with an instantaneous DHW system. You do not open a new H2k file since there is no tank part to model.
Combo systems that use a boiler--DO NOT use the Combo heating DHW system in H2k. Boiler and DHW have to be modelled separately.
Select boiler. Use induced draft if afue is less than 90% and condensing if over 90%.
Use "calculated" for output capacity, and Efficiency in Afue. In info field add "workaround"
With or without an Indirect fired storage tank
With Indirect
non condensing or condensing
make a new h2k file, click Combo Heating DHW, use same energy source as boiler, if AFUE is less than 90% use Heater w/ induced draft fan. Under combo tank and pump select proper volume, and note H2k' default EF
In the DHW part of the tree in orig H2k, use same energy source, under Tank Type, select direct vent sealed. Fill in proper volume, and User Specified EF from that you got from before.
if it's condensing, the EF will be .79
Without indirect
From House tree click DHW, use same energy source as boiler, then select instantaneous. For EF input as .72 for non condensing, and .79 for condensing