Tacocomfort wet rotor circulator (0015E3)

[Matthew Bohas]

Hello everyone

I have a 2 zone system and am trying to understand setup's a bit better as this is my first year in the house (renoation)

Navien NCB240

I have 2 taco pumps setup model 0015E3 that have 3 speed settings (low/medium/high)

If only 1 zone is on I find there is not a large gap between the supply and return water temperatures and I was wondering if changing the speed setting from medium to low would cause the gap to increase?

There are 5 loops of roughly 200 feet each of plex tubing on the first zone and 4 loops of roughly 200 feet each of plex tubing on the second floor.

Initially both are setup as medium for speed.

When both zones are on at the same time the supply vs. return temps are about 9 degrees F apart which is ideal, however when only 1 zone is on I find it drops to about 5 degrees after a bit.

The combi boiler is in the basement if this makes a difference for the pump settings

 

[Dana]

Hello everyone

I have a 2 zone system and am trying to understand setup's a bit better as this is my first year in the house (renoation)

Navien NCB240

I have 2 taco pumps setup model 0015E3 that have 3 speed settings (low/medium/high)

If only 1 zone is on I find there is not a large gap between the supply and return water temperatures and I was wondering if changing the speed setting from medium to low would cause the gap to increase?

That should be the case, generally. At lower flow more heat is lost along the loop resulting in a lower return water temp. But it's probably plumbed primary/secondary with the primary being driven by the internal pump on the NCB through a hydraulic separator. If the internal pump's (lower left corner in the picture below) flow rate is very high slowing down the secondary pump on the zone radiation may have only a small impact.

The primary pump's flow rate doesn't change whether it's just a single secondary loop or both secondaries are running, so the delta-T at the boiler will always be smaller when only a single zone is operating, even if the delta-Ts on the zone loops are large. If you have an infra-red thermometer, read the temp of the PEX where the loops tie in at the supply manifold, and where they tie in at the return manifold. It wouldn't be surprising to see loop deltas of 15F or more, even when the delta at the boiler is only 5F - 9F.

There are 5 loops of roughly 200 feet each of plex tubing on the first zone and 4 loops of roughly 200 feet each of plex tubing on the second floor.

Initially both are setup as medium for speed.

When both zones are on at the same time the supply vs. return temps are about 9 degrees F apart which is ideal, however when only 1 zone is on I find it drops to about 5 degrees after a bit.

The combi boiler is in the basement if this makes a difference for the pump settings

Being in the basement has no effect, but it's safe to run the zone pumps at lower speed. Given the 9F delta-T when both are operating at medium speed it's unlikely that even running the -0015s both set to LOW the delta-T would ever be so high as to stress the boiler. (I'd be inclined to run them both at low as long as the radiant floor temps stayed reasonably even, with no extra-cool or extra-warm spots due to the low flow and high delta-T on the radiation loops.)

 

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[Matthew Bohas]

Thanks.

I actually have temperature readings at the supply and return as well, I find it's a bit higher than what the boiler says but only a few degrees. I have the navilink so I monitor it closely.

I took a picture of the pump unsure if that is the setting for speed, either way I just left that alone and turned the taco pumps to low.

Temperatures are swinging a lot here in Toronto, probably will not have the heat on tomorrow to check if there is any difference, but will update the thread once it cools down again

 

[Matthew Bohas]

Thank you