trying to trim circulators

pexhead

A simple question I hope.  Is the circulator circled n this schematic really necessary?  I have the system configured as this Tarm diagram shows.   I am adding a radiant loop to my two zone radiator loop. They are fed by a Tarm Excel 200 with surplus heat going to an STSS   660 gal storage.   I am think about putting zone valves on the two radiator loops and feeding them by one  Grundfos alpha .  the radiant loop will have its own circulator.   Do you think  i could break the loop  at the x in the diagram and eliminate the circulator and termovar valve circled.  I understand the need for primary and secondary loops but wouldn't the circulators for the loops drive the secondary loop without the need for this circled circulator.  thanks for your thoughts.

Ironman

A Couple of Things

First,

How are you going to control the water temp to the radiant? Is it in slab or staple up? Either way, you'll need something more to provide the lower temp required.



In answer to your question: no, you cannot remove the "termovar" valve. If you do, there will be no way to pull heat out of the storage tank. If you remove the circ, then you'll have a control issue to address. It's somewhat of an unusual arrangement.

clammy

tempering valve

                   i would stick to tarms diagram  that 3 way valve is there for a reason it is to ensure that the boiler return temps remain hi .Low return temps on solid fuel boilers like yours is not advisable due to the formation of cresolenot only in the boiler but also in your chimmey .Is your storage tank open or closed .You could draw off the storage tank instead of the boiler i have only work on one of these types of boiler an would suggest you follow there piping diagrams or contact them and ask what they suggest .Do you have  gravity over heat loop as suggested by tarm ? peace and good luck clammy 

Zman

Pumping Away

You should be pumping away from the expansion tank.

You must control and this in manner that will prevent low return temps as Clammy pointed out. The gravity dump is also essential,in the event of a power outage.

I  prefer a design that has more "hydrolic separation" and uses injection mixing with outdoor rest on the radiant side and something a little less clumsy for the storage tank. I am having trouble getting my head around the "2 way traffic" on the storage tank. Just my opinion.This design must work fairly well or they would change it.

You could consolidate the 3 zone pumps to one and use zone valves.

Carl

pexhead

thanks ironman

i don't have the radiant loops on the diagram.   I will be using a mixing valve and circulator and drawing off the feed from the boiler to the tank.  the termovar I am considering eliminating  sends hot water back through the secondary  loop when the radiator reuturns exceed 165 deg. , allowing boiler output to go directly to the tank.  There is another termovar on the primary loop to maintain boiler temps.  

pexhead

thanks ironman

i don't have the radiant loops on the diagram.   I will be using a mixing valve and circulator and drawing off the feed from the boiler to the tank.  the termovar I am considering eliminating  sends hot water back through the secondary  loop when the radiator reuturns exceed 165 deg. , allowing boiler output to go directly to the tank.  There is another termovar on the primary loop to maintain boiler temps.  

pexhead

thanks guys

I have installed 7  165' 1/2 pex radiant loops under wideboard floors with Watts flex plate .  3 runs in 20 inches between each  joist.  Insulation is 4 inch blueboard with foil glued to the top side   The radiant feed is not shown on the diagram.



My radiator loops are 1/1/4 copper, cast iron raditors with monoflo tT s   fed by grundfos 15-58s.

The Tarm setup has worked pretty well so far.  When the boiler is not running and a zone calls for heat,  the zone valve zv -1 opens and circ C1 pulls flow from the tank  through secondary  loop with the radiator loop circulator ( P1,2,3)  pushing flow through the radiators and back through the termovar TV 2.  If the return is above 165 deg then TV 2 runs the flow back up to C1, if it is cooler , TV 2 stunts it either back toward the termovar on the primary loop TV 1 and/or back to the tank.  

When the boiler is running and a zone is calling for heat , primary circ  C3 pushes some flow  to the secondary loop through c1 and some  to the tank by the pipe just before zv1  if TV2 senses 165 deg return , then more boiler  flow goes to the tank. when zones are satisfied. ZV1 closes and all flow goes to the tank ,returns to TV 1 where it is mixed with hot water off the boiler . i hope that clarifies the two way flow.  It works ok but there just seems to be too much STUFF.

It  seems like I ought to be able to  put an Alpha on C1 with zone

valves on the radiator loops. . Right now some secondary flow comes back to TV2 without going through the radiators.  i should be able to break that loop and push all of the secondary loop flow

through the radiators,  That

loop woulld then never return 165 deg water so I could eliminate  TV 2 in the secondary loop.      Am I on the right track?? I  would reallly appreciate your input on how to make this simpler..  What do your mean by hydrolic separation Carl ?



Thanks Guys,



Tim

Zman

Preference

Tim,

I wasn't suggesting a total redesign. The original design looks like it works fine. The expansion tank location could use some improvement.



There is potential for the circulators to "compete" with each other. As the mixing valves turn the forces and flows change making for a potential for some undesirable results.



In my mind, a better overall design would have a big loop with the boiler, storage tank, and a heat mixing pump tied into it using closely spaced tee's. The boiler return temp would be protected via controls on the storage tank and mixing injection pump.I also prefer Chevy Trucks.



I think the other comments regarding your modification are valid. I am thinking you may be better off leaving well enough alone. You system works albeit a bit clumsy.

Carl