Continuos circ. question....................Casmo

TJ

You might try using a Tekmar 369 to control the zone pumps and to provide a temperature input to the Tekmar 363 injection controller, for the appropriate temp for the injection loop. Assuming the greatroom has the highest heat loss or heat gain, you can configure the 369 to run this circuit constantly or near constantly. The two other circuits will kick on and off as needed. I used this set up in my own home and it works well. I have almost the same set up you describe, 3 zones with one being a heavily glassed greatroom with a tile floor and the other 2 zones predominantly hardwood flooring. You will of course need to provide indoor feedback for each of the zones. Check out the Tekmar website liturature for the 369 controller for complete info on setup to use with the 363 injection controller. WARNING! - I'm not a contractor or in the trades; just an engineer.

Cosmo

Who has done this, and did it work

Hi everyone, I have a job I am working on....a post and beam home. The main living area ceiling peaks at 26' with a lot of glass. The whole system will have 3 zones controlled by pumps off of an injection loop (tekmar controlled), these will be outdoor reset. I would like to have the main living area under constant circulation, the problem is figuring a way to prevent ghost flow through this zone when the other two zone pumps come on within the reset injected loop. I would have to create a second injection loop to do this. I couldn't find much info on this in my reference collection (it is growing into it's own library!). Please let me know what you guys may have done for this. Thanks, casmo

Casmo

eleft(retired)

Ghost flo

Cas,

"• There should be a minimum 1 foot drop to create a thermal trap in order to prevent convective heat transfer through the injection loop."


I have not done this and it is a quote from Tekmar e021. Attachment posted in case you don't have it.

Keep up the good work,

al

hr

Actually

A properly designed ans set up reset control will give you near constant circ anyways. If you tinker with the curve settings you will get a system that starts a 68 degrees outdoor and modulates to the load all season long.. Combined with indoor reset or RTU's this may be a good option for you.

Ghost flows should be handled with proper piping and check locations. Ma nature hates an imbalance and will go to great lengths to equalize a hot and cold imbalance in piping. It can be handled with some careful design. this article may help with ideas.

I feel much better with a positive check stop, or zone valve, as opposed to thermal drop, I have had mixed results with "drops" and had to redo a few over the years. Hard to know how many inches are sufficent

hot rod

http://www.pmmag.com/CDA/ArticleInformation/features/BNP__Features__Item/0,2379,13972,00.html



To Learn More About This Contractor, Click Here to Visit Their Ad in "Find A Contractor"

eleft(retired)

as usual

hr,

Good article.

I put the zone valves on the return as close to the boiler as possible and a flow check coming out of the boiler before the pump. No noise no ghost problems.

I think Cas has a different concern, it sounds like multi temp from the variable spd injection loop with constant circulation..???


I would think just use zone valves & one pump


al

Cosmo

Yes Eleft, your right

My question was really how to control a continous circ zone, combined with two other zones (pumps not ZV's), that recieve heat from one injection pump. What about using a taco bypassing 3-way valve, this could isolate the constant circ loop from the injection loop until hot water is needed, then it would let hot water in as needed. I guess I used the ghost flow term wron, I just meant to say I wanted to prevent the constant circ zone from getting heat when the other two zones called. I have to buy Visio and show what I mean instead of trying to put into words! See the attached pics I pulled of the Taco site. Please more opinions!



Casmo

Frank_3

Two cents from a non-contractor ...

I've tried figuring this one out for my own system and the only thing I can come up with is using a seperate mixing valve for the constant circulation zone, with its own circulator, naturally. The other two start-stop zones would have to have their own circulator and mixing valve as well. I'm not sure how this would translate to using an injection loop. Maybe the drawing will help.

Oh, the mixing valves look backward but if you visualize how the valve will operate as it tries to establish the right temperature you'll see it's piped correctly to modulate the return temperature.

eleft(retired)

opinion

Cas,

All zones to be at the same temperature as constant circulating loop. One circulator pump (sized for all three loops) with a differential pressure regulator in a bypass loop. A zone valve at the return of each of the other loops.

al

Dan_8

not sure if this'll help

I might be just flapping my gums here but I've been thinking about this one lately for a job of my own. It seems that the 'utility loop' in this article might be what you're thinking about:

http://www.pmmag.com/pm/cda/articleinformation/features/bnp__features__item/0,2379,78589,00.html

If you used one of those three zones as the feedback to your controller (362?) I'd think that would work fine. If piped correctly the primary/secondary nature of that loop should negate any ghost flows I'd think.

My only concern with this idea has been that the other two zones would have a definite ceiling on how much heat they could put out since the temperature of the utility loop will be driven by the needs of the constant circ zone. You might have to design the other loops for a lower than optimal water temp just in case.

Anyway, take the above with a bag of salt as I've never built one but it seemed like it might help so there it is.

- Dan

Cosmo

Thanks all...

Tom, how did you know I was using tekmar? Yes, the only question I really had was how to valve on/off the heat to the constant circ loop, I think I found my answer in the taco 3-way valve. When the zone doesn't need any heat the 3-way valve will be closed and bypass the secondary loop carrying the tempered water (injection loop). When the zone needs heat 24volts from the 369 control will open the 3-way valve, letting in heat from the injection loop. When I have this stuff soldered up I will show you. I was looking for different methods of doing this. Thanks also to Eleft for the pics. Thanks for all the responses.

Casmo
Dependable P.H.C. Inc.