Vertical Spirovent efficacy?

archibald tuttle

so i was bemoaning the lack of parts for an old spirovent the other day, but upon refilling this system I realize that the theoretical ideal location for the vent would be on the vertical because this is a indirect tank feeding radiant floor and it is so convenient to just set the pump on top of the outlet of the tank, but that is leading to occasional circulation loss to cavitation to gas being released from the water in tank on heating.  It hasn't helped that my existing spirovent has to be hand vented so i don't get ongoing air removal except manually, but ideally the spirovent should be between the heat source and the pump.



So while i'm still griped that i can't find parts for the older spirovent currently installed, and while i do think that I could -nonetheless -- just put a street el and hi vent on the outlet of that old spirovent (its 1/4" pipe thread) and get sort of effective operation, I thought maybe i should just abandon it and use a  vertical.



But in looking at the vertical style spirovents it isn't the 20% cost increase that really puts me off.  I don't think they did that great a job designing the flow chamber for air elimination. I would think you would want a much wide chamber around the pipe circumference with an obstacle in the center to force flow to the outside and then a channel at the top of the chamber the ushers air up to the outside while allowing water to return to the outlet at the center.



I can't see in the interior geometry of these verticals and i guess i generally give the relatively original vent company some credit for having considered these issues, but i'm wondering if anyone has used these spirovents or i see caleffi has an equivalent where i found a diagram that seems to show -- although it ain't that great a diagram -- that the flow is diverted sideways under the vent assembly and then back in line.  It is hard to tell if it really diverts all the flow that way or is implying that it is able to divert gas bubbles.



The Caleffi is about 20% more and has a kind of top that theoretically makes service and cleaning easy but i've had leaking problems with the Sparco vent using a similar top design.  Perhaps they worked out their washer/o-ring better.



And all these companies don't seem to market parts or rebuild kits, only expensive new upper halves.  I'm not particulalry impressed with that approach but don't seem to have so much choice.



So looking for results with vertical format vents from anyone who has any field experience with them.



thanx



brian

archibald tuttle

extensive wall searching

reveals many references to the use of vertical spirovents.  one thread in which it gave the appearance of not working but that was never resolved.  mostly they continue to be recommended as a way to get the vent between the boiler/heat source and the pump.



I think this would be helpful in my case but eager to hear that folks find them doing their job.





i still haven't been able to find a picture of the internal geometry but it does appear from a closer look at the exterior that the water flow is shifted horizontally to the vent outlet and then back to the pipe in which case i'm a little more inclined to to intuitively believe it will work, but love to hear positive results from someone who has used one to add to my intuition.



they'll probably be at AHR but all the more reason to take any reflections i can gain on the wall with me when i try to button hole them next week.



any takers.



brian

hot_rod

the features

The main goal is to remove all the air, from the largest bubbles down to the dissolved and entrained air. A top quality product will do this across a wide range of flow conditions. Notice the size of the passageways, a vertical separator puts a lot of turns in the fluid path. Wide oval shaped designs minimize the flow resistance.



Some brands test out to 10fps, way beyond normal operating conditions in a hydronic system.



Another detail is the Cv or flow rate that the device can handle.



Equally important is the ability to easily service all the components of the vent. Ideally you should be able to repair or replace any and all the components from the media inside to the top air vent assembly.



In some brands it is possible to service all those parts with a hand tightened dis and re-assembly.



All brands have the potential to plug up or leak, it's not the fault of the product in most cases, but the fluid quality, and operating conditions within.



Compare products and look for one that can withstand the poorest of fluid quality, operate in the high 90% efficiency range, and be service-able in place.

archibald tuttle

hot rod - or anyone - want to talk vents at AHR next week

thanks for run down on design component considerations.  would like to take this up over a beer. you gonna be in NYC next week?



so are you saying that the passage designs actually causes an acceleration of flow?

as far as the maximum flow rate, i don't think i'll be in that kind of territory on this job, but i assume you are talking about a maximum flow rate at which good or full air elimination can occur?

are the verticals and horizontals in similar sizes generally equivalent in design max flow rate?

 i'm assuming that the vertical models have more resistance than the horizontal so they add a little more head?



as best i can guess on the couple i have looked at, i.e. spirovent and caleffi, the flow is shunted in a brief horizontal U with the actual vent located at the upper apex of the U off the side of the main piping.



i have been a big spirovent fan, partly because they were the original as far as i was aware, but i'm open to hearing other's favorites -- vertical and horizontal.



the one time i went off the reservation when competitors began to spring up with a sparcovent -  now i think those are supervents and have been brought under the honeywell family - that hand disassembly feature turned out to be a nightmare because the gasket on the removable top started leaking only a few months in and i could not make it stop. tried new gasket same result.  finally a whole lot of silicone and got it down to a drip.  it was gruesome.



so i was impressed when a spirovent i've had in service for 25 years came right apart with a couple wrenches. yeah, you can't do it by hand, but it wasn't welded shut or anything.  i the air vent was leaking water and i took it apart to service. 



but thats where things went wrong. apparently spriotherm doesn't believe in service. they don't have service parts for the internals.  the only part they seem to offer is an entire new top (at the price of the better part of a whole new vent).



to add insult to injury, mine is the 'old' type - they know all about it, they describe its difference in looks -- and then happily tell you it came from europe and you can't get any parts for it.  well europe is that terra incognito.  of course we can't get anything from europe and apparently we don't give two hoots about anyone stupid enough to have been using our products for 20 years or more.



a solid bronze lifetime vent becomes scrap because it was made in europe? so i'm thinking to myself, what happens if they start making some new casting in china, am i not going to be able to get parts for the ones they presently make?



when i called spirotherm's rep they acted like there must be something wrong with my system that the stainless element was corroded and that the top was leaking.  well my system is hydronic. you know it has water in it and dissimilar metals and it is an older system on polybutyl before oxygen diffusion barriers, in other words like virtually all the systems being put in 25 years ago.



in the same house, no less, i've got 65 year old steam traps that i have no trouble getting new tops and elements for. i don't know what is up with folks who claim to be manufacturing the cats meow in heating equipment and then look the other way when it needs to be rebuilt after 20 years in service like you should just buy a new one.  According to common wisdom i should have thrown away all my heatmakers by now which are all doing just fine in non-condensing applications - which is the vast majority of applications in the US - with the exception of the steel HW tanks ... but i digress.



i still think spirotherm seems to know what they are doing at the native tech level but i was very disappointed in their service orientation, as in what service orientation, so i'm open to recommendations for other vertical separators that anyone thinks have been proven in operation both from a native tech but also from a serviceability perspective.



i'll be beating the aisles at AHR next week but like to be loaded with wally prejudices . . . eer i mean preferences.



thanks,

archibald tuttle

relevance of sediment feature

hot rod,



realize i wrote a novel there, but i realized the distilled essence is that you think servicability of vents is important and spirotherm thinks they shouldn't need service and if they do it isn't the vent that is the problem.



now, i'm not saying there is nothing to that point of view but i don't think it is realistic to expect ideal operating conditions. they also assumed, until they heard the age of the unit involved, that excessive corrosion might be related to antifreeze . . . and this is something you don't anticipate in hydronic service?



and for my next novel, what about sediment trap feature. it brings to mind one other design distinction. some air eliminators have kept the format of water feed and expansion tank attachment on the bottom, whereas others have created dirt drop/separator motif.  In my system - admittedly old install with cast iron heat exchanger and pump and polybutyl tubing - the cage unit was corroded, not to non existence but getting there and it was maybe 1/2 loaded or blocked with rusty sediment.  but i think that might have tended to deposit on the cage anyway rather than settle to a sediment trap. and if you have purge nearby -  maybe to both sides, you could clean the cage a bit by purging through the bottom fill.



and the extent of cleaning sometimes needed does make me wonder whether these would be appropriately install with unions or flanges so you could easily get the whole body down for rinsing out.  I notice that is the case for the really big commercial ones. or maybe regularly colocated with the pump.between the flanged shutoffs allowing that kind of service with minimal system disruption.  design on verticals might have to give slightly more room for pump body and horizontals would need good support.



just thinking out loud.



brian

SWEI

I've always questioned

the utility of having the sediment "fall" into the expansion tank.  I always spec either a combo air/dirt separator or a multi-funciton hydro separator.  Air vents on top are valved off for easy service.

archibald tuttle

SWEI what kind of valving or access for the main separator

and do you tee supply and expansion tank generally just upstream of the separator?



brian

SWEI

Valving depends

on the rest of the system.  If there's a single boiler, I'll put valves on that side of the hydro separator.  With multiple boilers, we've already got isolation valves on each, so the utility of another valve at the seaprator is minimal.  We us copious quantities of Webstone Ball Drains on the distribution side, so rarely a need for valves on that side of the separator.



Expansion tank with isolation and drain valves usually teed off a cold leg of the hydro separator.

archibald tuttle

cold leg?

don't quite get that reference.  are you talking tee out the bottom but don't put the tank right under, move it over or is the cold leg the downstream side, i.e. further from boiler, by convention since it won't be colder than the upstream leg except by the tiniest amount?

hot_rod

manufacturers strive

to upgrade and improve products they offer. Keep in mind most customers want the best value for their dollar. So a manufacturer needs to balance the "uber" product against what the customer will actually buy.



Material selections evolve also, as the current low-lead mandate plays out expect to see more composites being used, so some brass products may be obsoleted just by the brass mandates. There is a limit to what a manufacturer can, or may want do with these new, low lead brass alloys.



In your case the challenge is the PB tubing, as you know that is probably the cause of the conditions inside your system. If the tubing is to stay in the piping circuit, shop around for components that can best handle those conditions and be user friendly when they do (will) need repairs.



Took my 8 year old i-mac in for a hard drive repair last week. They did have a drive to replace the bad one but told me all other repair-able components are now obsolete.



Stop by and chat when you are at the AHR show next week in the Big Apple.

SWEI

Hydro separators

have two "hot" ports and two "cold" ports.  Hooking to any port makes the entire device the PoNPC.  I use one of the cold ports to minimize thermal stress on the tank.



For a two-port combo device (air and dirt separation) you can pipe the tank anywhere nearby.  I've done one or two where the tank was piped off the (vertical) drain leg with a horizontal tee.  Drain leg needs to allow regular blow-down of the dirt separator.