Apologies for the length of this topic but it is something that crops up all the time and now seems more important as the energy modelling is now part of the permitting process  here in BC. Open to offers lads, and lasses!!

I have a few queries that I'd like you to pass on to NRCan for advice and/or clarification. They are in regards to very common heating and dhw set ups here, and can also have some sway in the step code calculations we now use for building permits.

In 9.36.5 it states that the heating "firing sequence"is Type2, then Supplemental, then Type 1. Is this the same for 9.36.6?

Scenario 1.

In floor radiant heating in the basement + either direct or indirect dhw.(combo/dhw) A single main floor above heated by a furnace. The main living quarters are on the single main floor.

To model this would you use the furnace as Supplementary 1, usage always, so it becomes the main heating source and is used before the 'combo/dhw' Type 1?

Presumably the same to be done for two storeys above the basement?

Scenario 2

A bigger problem occurs when the house is a two, or three storey slab on grade and only the ground floor is heated using a combo/dhw radiant system, and then has a furnace for the one or two floors above. If you checkmark the slab on grade radiant heating box at 100% then, I believe, that H2k uses that to assume that the whole house is heated from that. Also, if it is heated through a boiler the capacity of the boiler will always be plenty enough for the full heat load as the boiler is also sized for the hot water too. How should we model this if the floors above the ground floor are heated with a furnace, which may, or may not, also be used in air conditioning. Would we still use a furnace as Supplementary 1, usage always, and would this then 'override' the radiant section?

Very much the same problem, this time from the end of July last year!

I believe the sequence of heating in H2k is Type 2, then Supplementary, then Type 1.  If there is no Type 2 then the sequence would be Supplementary then Type 1.

Can you please ask NRCan what would be the correct way to model the following heating systems within a house.

A radiant basement floor from a boiler that also provides dhw. Two upper floors heated by a furnace.

I would use 'Combo heating/dhw as type 1 and then Supplementary for the furnace setting the usage as always.

If the output capacity in the heating screen is set to calculated then that will show the Btu or Kw required from the heating system for the whole house.

There seems to be no way to split the two floors of furnace heated area from the heated basement area.

If Supplementary is set to always then this will run until the output capacity is satisfied and then start to use Type 1. In reality the furnace would always have a larger output than that shown in the output capacity having the effect of the basement heating never coming on.

If the Supplementary is set to never then the same will apply but only the boiler capacity will come into play. As boilers that also provide dhw will have a higher output then H2k assumes that the boiler is capable of heating the whole house as the output capacity is always covered by the boiler output.

Is there any way to adjust the Supplementary heating (furnace) to give a more accurate and real life figure for the heating systems. The Supplementary only has a floor area as a setting so the % of usage does not take into consideration other aspects of the house design.