# Tarm mixing valve setting?



## nporter (Jan 4, 2009)

A question on my Solo30.  On pg. 54 of my manual, in the Specification Data table, it refers to the Mixing Valve Opening Setting and states that it should be 140°F.   So what is that referring to?

I am befuddled to say the least!


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## Nofossil (Jan 4, 2009)

I don't know what Tarm is referring to, but 140 is about the right temperature for input protection. You don't want really cold water coming into the boiler, and that passage might refer to the setting for a mixing valve that ensures that incoming water is hot enough to prevent condensation.


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## nporter (Jan 4, 2009)

Thanks nofos,

That sounds like what they might be talking about. I think that the Thermovar would do that mixing but don't know that it can be "set" to a certain temp thus my confusion.


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## Nofossil (Jan 4, 2009)

Than Porter said:
			
		

> Thanks nofos,
> 
> That sounds like what they might be talking about. I think that the Thermovar would do that mixing but don't know that it can be "set" to a certain temp thus my confusion.



I think the Termovar has a thermostatic cartridge that's replaceable and available in different temperature settings. Their instructions might assume a different type of valve.


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## flyingcow (Jan 4, 2009)

My system should be up and running late next week(solo 30 innova w/800 gals of storage), but I'm using the termovar loading valve. Plus the diverting valve. Pretty much following tarms plans/and equipment, got valves from them,so I'm assuming settings will be by their specs(but I'll check). If I have problems down the line I can trouble shoot on my own. Not terribly clever with plumbing.


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## sweetheat (Jan 8, 2009)

I was very befuddled too. for a non plumber or layman it seems they are not so clear on this. the mixing valve should be before the return termovar. directing hot water back into the return water. this will keep temps up to 140 for the return water going back into the boiler. Mine is almost closed, just a trickle is being sent back. sweetheat


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## jebatty (Jan 8, 2009)

> the mixing valve should be before the return termovar. directing hot water back into the return water. this will keep temps up to 140 for the return water going back into the boiler.



Do you mean that the mixing valve (balancing valve) should be on the boiler supply side to the Termovar to control boiler hot water flow into the Termovar?


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## DaveBP (Jan 8, 2009)

I'm confused. (What's new?). 
Is the "mixing valve" here the same as the "balancing valve" shown on all the Tarm piping diagrams. That IS between the Termovar thermostat and the boiler supply. They say to start with it half closed.

http://www.woodboilers.com/userfiles/file/Solo Plus Plumbing.pdf


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## jebatty (Jan 8, 2009)

I can't open the link reference.


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## chuck172 (Jan 8, 2009)

The balancing valve that tarm refers to is just a ball valve that can be throttled. 
I believe the mixing valve is the termovar.
The termovar mixes hot boiler supply water with the cooler return system water to protect the boiler. You balance this mix with a balance (ball) valve.


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## sweetheat (Jan 9, 2009)

a yellow handled ball valve above the termovar, up is open, down is shut. depends on your install position and the way you look at the lever. this mixes hot boiler supply water into the termovar. the termovar returns 140 degree water back to the boiler. sweetheat


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## hoth2oguy (Jan 9, 2009)

Chuck172 and sweetheat you are correct.  The balancing valve is simply a ball valve that we recommend is set half closed to introduce some head (resistance) prior to the Termovar so that water will be more 'inclined' to go out to the zones than to short circuit through the Termovar mixing valve.  The Termovar mixing valve mixes 165*+ water from the boiler coming into port one of the Termovar valve with relatively cool return water coming into port two so that water leaving port three and returning to the wood boiler remains above 140*.

nofossil, you are correct, the Termovar is available with several different cartridges that operate at different temperatures, but it cannot be 'set' or adjusted so I guess the wording in the manual is a bit odd.  Will have a look at that tomorrow, thanks for pointing it out Than.


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## nporter (Jan 10, 2009)

Thanks for all the "valve" education. I am still getting the balancing and mixing worked out and this thread clarified things for me.

The explanation of the Termovar makes sense to me and I was curious if the 140° setting referred to in the manual was the particular Termovar cartridge because my has 72° stamped on the side plate. 

So does that 72° relate to 140° somehow or do I have the wrong Termovar in the system?


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## DaveBP (Jan 10, 2009)

> 72° stamped on the side plate.




72 is the temp in centigrade degrees: about 160F. I don't know why Tarm supplies mixing valves higher than some other recommendations I've seen (140F is a favorite minimum). I would think lower return temps would improve heat exchange within the boiler. 140F seems to be the concensus minimum. 

Would the optimum return temp thermostat differ for systems with pressurized or unpressurized storage?


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## chuck172 (Jan 10, 2009)

The way I understand Chris,  the 160* element is located in port 1. Port 1 can be throttled (constricted) by the balancing valve feeding it. This sets up the restriction to force cooler boiler return water enter into port 2.
Then the mix occurs to push 140*+  water through port 3 into the boiler return.
A 140* element would mix with the cooler boiler return temp resulting in less than the 140* desired return boiler return temperature.


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## jebatty (Jan 10, 2009)

Chuck -- thanks for such a clear statement on the operation of the Termovar. Yesterday when I was charging storage, and return from storage was 140F and rising, I fully closed the balancing valve for the remainder of the charge. I will partially open it again when the boiler is next fired, as bottom of tank or system return will be less than 140 on re-firing.

Just for the fun of it, would it make any sense to have a zone valve along with the balancing valve on the line to port 1, and an aquastat or thermostat which would close the zone valve when the line to port 2 was 140F+? This would force all boiler output into the system. Is there any benefit to the boiler or operational efficiency to continue to feed boiler output directly back to the boiler to let the boiler return rise to 160F, for example?


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## chuck172 (Jan 10, 2009)

Jim, if you do that you can just rip out the termovar. Just use the aquastat and zone valve as the mixing valve. You'll probably have less restriction.
Thank Chris Hoskin from Tarm for the explanation of the termovar.


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## hoth2oguy (Jan 10, 2009)

you've got it Chuck.  The 72*C  (160F) designation is the temperature at which the valve starts to open port two and close port one allowing return water through the valve.  This results in the desired 140 return to the boiler.  Because port one never closes completely we recommend the balancing valve to get us closer to the ideal situation that jebeaty describes.  When using our Termovar loading unit (thermostatic valve with integrated circ pump and thermometers), however, port one does eventually close completely, so no balancing valve is needed.  Pretty slick unit actually.


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## chuck172 (Jan 10, 2009)

Chris, you really cleared up the workings of the termovar. I had no idea that the termovar loading unit automatically closed port one.
As I told you on the phone, your continued input to this site is really appreciated.


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## Jackpine Savage (Jan 10, 2009)

Chris, is there more information available on your Termovar loading unit? I'm just starting my Solo 40 install (I've had it sitting in my garage for over a year), so I haven't seen any recent sales literature.

On a somewhat related note, I've been trying to decide where to place my circulating pump. I have John Siegenthaler's book that recommends placing it after the expansion tank on the supply side. But I've 'heard' that the Termovar may not work correctly in that configuration.


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## jebatty (Jan 10, 2009)

> Because port one never closes completely we recommend the balancing valve to get us closer to the ideal situation that jebeaty describes.



I first noticed the effect of this yesterday, when my system return water to port 2 was at 150, port 3 to boiler was at 172. It was at this point that I closed the balancing valve completely.


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## DaveBP (Jan 10, 2009)

> is there more information available on your Termovar loading unit?



Click the 'products' tag. 

http://www.acaso.se/english/index.html

I have been eyeing the loading unit for my pressurized storage install. Expensive but elegant.

Chris, if the loading unit WITH the backflow preventer is installed with a closely couple pressurized storage tank can it actually thermosiphon enough in a power failure to take the boiler load without an 'emergency load through automag' setup as in your diagrams? I bought a Solo 40 from you but haven't installed it yet and so have time to fiddle my system design before this summer's actual installation.


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## flyingcow (Jan 10, 2009)

Jackpine Savage said:
			
		

> Chris, is there more information available on your Termovar loading unit? I'm just starting my Solo 40 install (I've had it sitting in my garage for over a year), so I haven't seen any recent sales literature.
> 
> On a somewhat related note, I've been trying to decide where to place my circulating pump. I have John Siegenthaler's book that recommends placing it after the expansion tank on the supply side. But I've 'heard' that the Termovar may not work correctly in that configuration.



I'm sure Chris Hoskin can provide you with a link, but I'm not real good with these computers. Go to Tarms website, click on scantec solo boiler, click on plumbing schematics. There are 10 pages of various setups with the termovars with and without storage. I've got more info on the termovars, but don't know how to post it here. Got to get my 10yr old to do it.


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## hoth2oguy (Jan 10, 2009)

http://www.acaso.se/english/produktblad/TERMOVAR Ladd-paket EN 0502.pdf   

is the link directly to the loading unit .pdf.

Jackpine, while "pumping away" is a good practice in general, you need to pull through a mixing valve as I understand it.  That is why we show our C3 pump between the Termovar valve and the return on the woodboiler.  We know this setup works well, but there is some discussion around the office about if this is true or not.  Would appreciate any thoughts anyone has.

DaveBP, I am not sure about two things: first, I am not sure if the loading unit we stock ships with the back flow preventer or not, second, I am not confident about how well a thermosiphon would work through a tank.  As you know we recommend baseboard element equal to 10% of the rated output of the boiler be mounted high up on the boiler room wall for a power-outage dump zone.  We know this works, but I am not sure if the thermosiphon through a pressurized tank will flow enough and/or radiate enough heat away - especially if the tank temp is already high.  Does the vertical distance of a thermosiphon improve it's effectiveness?  In other words, if a couple of baseboard elements are mounted ten feet above the boiler will it dump heat more quickly because of increased flow than the same setup mounted five feet above the boiler?  Or is flow through both setups identical?  Not sure if it works like that. Thoughts?


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## DaveBP (Jan 10, 2009)

Now I see what's going on here. The automatic URL linking and underlining feature on this forum stops if there is a space in the URL so that it doesn't pick up any characters after the space and so you get the 404 error. You have to copy and paste the whole thing into your browser's address bar to get it all. 

Chris, your link directly to the loading unit did the same thing one of my posts recently did. The URL works, you just have to manually punch all of it in.

At the bottom of the second page where it shows the cutaways of the unit with and without the back-flow preventer it says "In case of power or pump
failure the backflow preventer will open automatically for self-circulation". Of course, the amount of that flow and whether it is enough will depend on a handful of factors.I don't think there is a simple answer. It depends on too many variables. I just wondered if your mad scientists out back there had done any tests.

 When I was there to pick up my Solo 40 I asked a bunch of questions and got a great tour of operations in the test facilities in back. Travis (?) told me that the loading units with the back-flow preventer were not stocked at that time but might be in the future as they were intended for use with pressurized storage. Your pressurized storage units were not out at that point but being tested. 

I have some physics background but no hydronic heating experience. Thermosiphons run on the difference of density between water in one tank and another. The colder denser water will want to settle to its lowest point because it's heavier than the stuff above it. I don't believe the height difference changes anything as long as the water can settle DOWN into the boiler and push the warmer water UP back to the storage. There are people on this forum who might have experimented with this.
perhaps on sidearm DHW setups. I don't think one should be loading a lot of wood into the boiler if the storage tank is close to full, so there might not be a lot of BTU's to absorb for a long time.

I appreciate your posting here. It helps a lot to narrow down some of the speculation that we indulge in here to have somebody " on the inside" to answer so many questions and point to other sources of information.


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## Rory (Jan 10, 2009)

My Termovars have a little arrow on top that can be turned.  The rep from Revision Energy had me turn it to 45 degrees (compass), saying that would cause a little restriction and it would work better.  He claimed that the Termovar is basically a ball valve.


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## nporter (Jan 10, 2009)

Chris Hoskin said:
			
		

> The balancing valve is simply a ball valve that we recommend is set half closed to introduce some head (resistance) prior to the Termovar so that water will be more 'inclined' to go out to the zones than to short circuit through the Termovar mixing valve.  The Termovar mixing valve mixes 165*+ water from the boiler coming into port one of the Termovar valve with relatively cool return water coming into port two so that water leaving port three and returning to the wood boiler remains above 140*.



Alright now that the Termovar has been explained I went down to check mine out and the port matching is not as Chris described. I understand Chris' explanation but if that is the case mine looks backwards. (not a first for me) So then I went to check out the Manual (p. 66) to see what that showed. It seems to indicate that the feed from the wood boiler goes in at port 2, port 1 is the return from the zones and port 3 is the return to the wood boiler which is what I have set up. 

I have port 1 restricted 45° angle but is that what I need? Isn't that restricting the flow to the zones? 

Does the Tarm design make sense as described above or am I just reading it incorrectly and should the Termovar be changed around to have port 1 matched with water from wood boiler and port 2 matched with return water from zones?

Still learning! It is amazing what one can learn through reading and taking few moments to digest it all.


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## hoth2oguy (Jan 10, 2009)

Thanks DaveBP, we have appreciated this forum and have sent people here frequently.  Especially if they are looking to come up with their own tank system.  Lots and lots of other good info too, of course.

Sorry about the link above, glad you figured it out.

I love the 'mad scientists out back' image!  Travis spent most of the week running tests in the dungeon this week and by the end of the week the label surely fit!  We are also fond of "boiler geek"!

What you say about the thermosiphon makes good sense.  Now that we have the pressurized storage, we will  have to get the back flow loading unit it to test.  Would be a nice set up.

As far as being on 'the inside' I am not the most technical person and I am sure I will mis-state something here eventually!  Good news is that there is a crew of first class boiler geeks here and at the office that will set me straight when I do!   Thanks for being here.


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## DaveBP (Jan 11, 2009)

I think there is a confusion of terms in this thread that I've noticed before in other threads. Termovar is a name that ACASO uses for a number of different thermostatic valves they make for different uses in  hydronic systems. Most often on this forum "Termovar" is used to mean the return protection device just before system water returns to the wood boiler. But there are other uses for other variations of these thermostatic devices. And, frankly, I don't understand some of the distinctions.

Than, I think some of the posts in this thread are referring to a different "Termovar" than the one in the zoomed in part of the Tarm diagram you refer to. It looks to me like the port numbers are different, too. Your closeup view Termovar is protecting the oil boiler, isn't it? 

But then I just spent the afternoon gluing foam panels to studs. Maybe too many fumes?


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## nporter (Jan 11, 2009)

DaveBP said:
			
		

> Than, I think some of the posts in this thread are referring to a different "Termovar" than the one in the zoomed in part of the Tarm diagram you refer to. It looks to me like the port numbers are different, too. Your closeup view Termovar is protecting the oil boiler, isn't it?
> 
> But then I just spent the afternoon gluing foam panels to studs. Maybe too many fumes?



Regarding the port #'s I agree the orientation is different and the port #'s are different but I was curious if that was simply a computer graphic orientation thing that was unclear in the manual or if  it really was to protect the oil boiler. 

Mine is set up with port 3 going down to the return, so it protects the wood boiler but I think that there may be issues with my other two ports.  Some times I am amazed that this thing is working the way it is presently set up. More research and alterations and we will be in a better place I'm sure.

I guess that a call to Tarm might be the next step for me because my mind is addled and there were no fumes for me today.


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## nporter (Jan 11, 2009)

DaveBP yes you are correct. I was assuming that the Termvar that has been installed is a mixing valve and we were treating it as such and it is one but....

As you pointed out, and what I was confused over, is the fact that the Tarm diagram is calling for a Termovar Diverting valve not a mixing valve. Only one digit off. (6440A-3 as opposed to 4440A-3) Thanks for causing me to take a closer look. Now things are starting to fall into place! At least for the moment. 

So looks like the mixing valve should come out and a diverting valve put in.  Hey at least the wood burns and makes heat. I just can't seem to get it moved around all that well.


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## hoth2oguy (Jan 11, 2009)

so just to be clear, yes, Termovar actually refers to several different valves mad by ACASO, but when we talk about it we are generally referring to the mixing valve close to the wood boiler.  This is shown as TV1, or in this case C3 (part number K4440A3) on our drawings.  Actually this drawing is showing the loading unit which incorporates the mixing with a circ pump - location F on the drawing is what I am trying to say.

Also correct that TV2 is a valve made by ACASO with the part number K6440A3.   We refer to this as a diverter valve and it is used in conjunction with storage.  If you have a K4440 at TV2, it should be replaced with a K6440.  Look very carefully, however, because the valves look virtually identical.  The easiest way to tell externally is that the red arrow / swoops on the aluminum plate look just a bit different from one another.  If I had to bet, I would bet you have the correct valve in each location as ReVision really knows what they are doing.  Stranger things have happened, however, so give us a call on Monday if you still have questions.


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## Miner3 (Jan 11, 2009)

I changed my Termovar because it leaked & I was not happy with the restriction. I posted some pictures in this older thread https://www.hearth.com/econtent/index.php/forums/viewthread/19586/


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## Miner3 (Jan 11, 2009)

Page two of the post shows the difference between the inside diameter of the 1-1/4" copper & the Termovar fittings.


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