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Basement single series loop; convert to direct return or ?
I am at my wit's end here. I've been crash-coursing for the last month on how I can get a little bit more granular control in my basement.
- Sq-ft is around 1100sq/ft for that level.
- Climate zone 6
- It is a single series loop of varying baseboard fin-tube lengths with 3/4" piping.
- Some bleeders on baseboard, other bleeders at 90-degree elbows on vertical risers of the loop. (some are leaking)
- Level is unfinished and open.
- Boiler is a Slant-Fin S-90 EDP.
- Pump for that zone is a Taco 007 on the return side of the boiler.
- Other level is heated by elements in the ceiling fed by a header and a B&G nrf22 - water temp is reduced with a mixing valve. ( I do not want to mess with this at the moment)
I'd like to implement some level of control using TRVs. From what I'm hearing these are nice for matching load, and coupled with a smart thermostat with remote sensors, would minimize electrical work with electronic valving. The only drawback I can see is the TRV can't be set-back at night or when there are no occupants in the house.
Initially I was excited to see some 3-way bypass TRVs. I figured the series was sized so elements down the line accounted for lost water temperature anyway so at design load, all TRVs open, the elements could still heat their areas. I was unable to find these 3-way TRVs. I did see a "bypass" set-up in baseboard (using copper tees and piping) to bypass the TRV and element with the TRV closed, but I never saw a confirmation of this working due to flow and pressure conditions.
Then I happened upon direct and reverse return designs. I've read that direct returns can work well with TRV and proportional pressure pumps. Reverse return has some balancing benefits.
I am not averse to doing some re-piping. I'd like to minimize expenditures on new things like a manifold and pex runs or convert to manifold zoning. I will if I have to, but if one of these other designs can work, I want to start there.
Any advice is appreciated. I am definitely willing to throw money at a heating person to do calcs or consult or quote and that is my next avenue if it looks like this is the direction I can take.