Taco 3 way Mixer cascade

adayton_2

is probably not significant across the Lawler as it is a ONE Inch (1.0") and seems to have a floating baffle temperature valve, so I believe it performs largely full flow throughput with only negligable incidental surface drag on flow. We would be using 1/2" Taco 3 way mixer since the old hePEX is 1/2", Unless you think it would be even slightly helpful to use a 3/4" Taco for any slight flow benefit (especially coming off a 1" Lawler mixer). The feed in and out of the Steamer boiler is stepped down from STD. 3/4" to the 1/2". Stock 3/4" Taco circ has been powering this hePEX for 10 years and does not seem to whimper at all. Tnx for you comments,

Alfred/Jim

adayton_2

Cascading Taco mixer

per attached diagram. You expert radiant guys see any drawbacks? Before you ask please confine your focus to the cascade issue ONLY....Standard "other" components such as safety pressure relief valve and street pressure reducer valve ARE installed. Left off drawing for simplicity. NOTE: there are however NO check valves except for backflow prevention. Mostly concerned about FLOW and PRESSURE related issues. Also any observations about CONTROL issues. This is currently operating fine without the Taco in the picture. I need to add the Outside Temperature reset feature to smooth out HO comfort and potentially improve fuel useage during outside temperature swings. Long Island, N.Y. Geography, assuming design temp at 20* F. This is a sensitive 10 year OLD hePEX install that was just "saved" after 2 tubing failures, so the Lawler mixer MUST STAY as a protective heat sink BRICK. :-). The Lawler is strictly a forcefull thermal-mechanical device with limited range abilities. Loop is operating at 9 PSI.

Thanks for any insights.

Al/Jim

Constantin

Whoops

Never mind my earlier post. I misread your diagram. If I understand it correctly, the radiant system is going to get "fed" using a coil in a steamer. I think it will work as drawn, perhaps give it some means to purge itself of dissolved air.

Joe Mattiello_2

pressure drop concern?

The pressure drop through both mixing valves is a legitimate concern, not to mention the redundancy. The CV for the ¾” I valve is 3.3. something to consider.

Joe Mattiello
Technical Support Technician
Tel. 401-942-8000 X 484
Fax. 401-942-2360
1160 Cranston St
Cranston, RI 02920
joemat@taco-hvac.com

adayton_2

Steam DHW coil

is what is feeding this radiant hePEX and even though the system has run for 10 years with no auto air purge device I would also like to instll one. What models/Brands do you recommend? Also why are they particularily beneficial over just doing a manual purge on install (set it and forget it??) ?
Tnx for you comments,
Alfred/Jim

adayton_2

Redundancy is

is not a major concern, the Lawler Tempering Valve merely happened to be available AND was a first attempt at "simply" and innexpensively as possible to drop the mad output high temp of the steamer DHW coil. Our PRIMARY objective accomplished, Now that the lawler is acting like a heat sink brick to effectively PROTECT the hePEX system, we are proceding to attempt to develop any potential flow/temperature efficiencies that may be possible focusing on outdoor temperature reset. This can be acomplished with the Taco 3 way -R installed per my diagram I believe. COULD we have used the Taco 2 way or 4 way right from the get-go?? Probably, BUT I feel MUCH safer this way with the Lawler "heat brick" in the path just in case Taco failed. :-) AND the Lawler is there already so is there any reason to lose the heat sink protection it is providing at this stage? i.e., why remove it at this point UNLESS it actually SUBSTANTIALLY interferred with the action or performance of the Taco? and THAT is the question that I pose. Thanks again for your comments,

Alfred/Jim

Constantin

If it isn't needed....

... then by all means omit the purging device. Perhaps a small loop like that won't benefit much from one.

adayton_2

Purge air

It is a single loop for a 12' X 12' room. it is running currently on 9 PSI and a brand new 4 gallon TXT. We can perform a manual purge every 6 months for a while to ensure any cumulations are gone. Thanks for the info.

Alfred/Jim