Dan - Two pipe direct return vs reverse return

TGO_54

Hi Dan-
In one of your books you talk about using TRVs in a two pipe radiator system( hot water). It states that there is no reason to use reverse return on the main piping because the TRVs will balance the system. Is there any reason not to use a reverse return other that the added expence?
Thanks

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DanHolohan

I think what I said

was that if you're using reverse-return the system will balance, assuming the pressure drop is equal in all the circuits. Once you add TRVs, the pressure drop will always be changing so it makes more sense to go with direct-return.

TGO_54

Hi Dan,
Thanks for the reply.
Assuming that the radiators are sized for the heat loss of each room on the coldest day, the TRV's should all be in the open position. If that is the case, then wouldn't the flow though the short run radiators be grater than the long runs? Would using reverse return eliminate or lessen the possabilty of this? I am laying out the supply mains for a panel radiator job, and the mains will just about make a loop in the house. It would be very simple to make the system a reverse return (no third pipe needed) but I want to be sure I am not creating a problem.
Thanks.

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DanHolohan

They should

but TRVs usually modulate when they're tracking the room temperature, trying to keep it within plus or minus a degree or so. Can't hurt to pipe it this way, but I'm not sure if it would make a difference.

TGO_54

Thanks for the advice Dan

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