Solo30 "mixing" issue?

[nporter]

Solo30 with 400gal pressurized is up and running. Fire burning fine, jacket temp came up fine, circ pump turned on it correct temp, the fan shut off when when temp reached about 188°, temp to tanks is reading 188° and temp return is reading 181°. The tanks are still cold and the fire is just waiting for some more fan action. When the temp in the jacket dropped to 170° the fan kicked on and the temp rose back up to 185°.

To me, a learn as you go guy, this seems like the return temp is too high and my question is, could it be a Thermovar issue? It seems like the "mixing" is not happening and the "hot water" is just being pushed around a fairly small loop.

The water in the tanks is cold but shouldn't there be some "mixing" of the cold with the hot to get the tanks up to temp?

Or am I just rushing things?!

 

[WoodNotOil]

You will need to close your balancing valve partway so less hot water is mixed with the return water. Start by closing it half way and see how it goes.

 

[sweetheat]

I had to close my balancing valve almost closed. Their is a catch 22 thing, you need to build small fires one after another to bring temp up. Once up you can build larger fires or what the weather calls for. Once you figure this all out it becomes easy. Burn every other day or once a day according to the outside temps. When its up to 40 degrees you can go 3 or 4 days with out draining the heat out of your storage. sweetheat

 

[nporter]

Thank you all. I will work on the balancing valve adjustments and keep the burns smaller until we get up to speed.

 

[jebatty]

I found with the Termovar that ideally, the cooler the system return the more open the balancing valve needs to be to achieve boiler return of 140-160; similarly, the hotter the system return the less open the balancing valuve needs to achieve boiler return of 160.

 

[sweetheat]

Jim: This is part of the learning curve. If your return temp is low you open the balancing valve to let hotter water mix into the return but if up to temp you only open it a small amount. I'm asking for advise on this issue. Why do they have the termovar? On the termovar it says 32 degrees celcius for return temps. Thats about 140 Faranheight. Do you turn the valve for each fire depending on return temps? Thanks for the help. Is their more info in another thread? sweetheat

 

[chuck172]

I think 9 out of 10 problems with wood boiler temps are due to the termovar. I found a spot on the balancing valve and I marked it, and just keep it there. Less than 1/2 throttle.
Remember each of the three termovar ports has its own ball valve.

 

[WoodNotOil]

I think 9 out of 10 problems with wood boiler temps are due to the termovar. I found a spot on the balancing valve and I marked it, and just keep it there. Less than 1/2 throttle.
Remember each of the three termovar ports has its own ball valve.

I think people using the danfoss are also experiencing some of these issues initially until they get used to them. Also, I think others use a zone valve and aquastat to inject hot water only when needed. I would be interested to hear from them as to whether that is more consistent, reliable, and easy to setup or not.

 

[jebatty]

Why do they have the termovar? On the termovar it says 32 degrees celcius for return temps. Thats about 140 Faranheight. Do you turn the valve for each fire depending on return temps?

Purpose of the Termovar is to maintain boiler water return temp between 140-160 to prevent condensation in the boiler due to cool water temps surrounding the firebox and resulting corrosion, thus extending boiler life. The firebox is coated with creosote, and creosote plus water = acid = corrosion.

I only adjust the valve on the boiler input side to the Termovar. I leave the system return and Termovar return to boiler wide open. I think three valves are provide also to serve as isolation valves for removal or maintenance affecting the Termovar.

Actually, I put in a gate valve on my 1-1/4 line to the Termovar, and I use this as the balancing valve, but the Termovar ball valve serves the same purpose.

I have had no operational issues with the Termovar of which I am aware. It appears to always have operated properly. The only issue has been the setting on the balancing valve.

 

[stee6043]

For the record I'm at least the second person on this site (first I heard of was Medman) that has received a Danfoss valve with the thermostat installed from the factory backwards. I discovered mine this weekend while finishing up the plumbing....

When cold mine was open between the system return and the bypass. Not between the bypass and the boiler return...

 

[Steaming Pile]

I use a shunt pump set up on my GW and it works like charm. It consists of a circulator, aquastat and a couple check valves. Set it and forget it like Ronco!

 

[chuck172]

I was taught years age that a gate valve is a positive shut-off, and should not be used to throttle. A ball valve or globe valve should be used to throttle.

 

[jebatty]

...a gate valve is a positive shut-off, and should not be used to throttle...

I think you are right. I used it because I had it, and I also understand that since this is mostly a "set it and forget it," issues arising from using it as a throttle largely are not relevant. Throttling, to my understanding, results in wear on the gate and seat from cavitation, which over time results in valve damage. I don't think this is an issue in this type of application. You raise a good point, though.

 

[DaveBP]

I think three valves are provide also to serve as isolation valves for removal or maintenance affecting the Termovar.

I think you're right, Jim. Termovar calls those "isolation valves" on their diagrams, not balancing valves. Thus the swivel nuts; so you can remove the Termovar for maintanence. The piping concept diagrams from Tarm (OK, Bioheat) show a "balancing valve" between the termovar and the boiler supply side and note it is "required".

 

[EricV]

My Termovar did not come with valves, should it have?

 

[jebatty]

The Termovar website shows the Termovar without isolation valves. It looks like this is an option. Talk to your dealer/supplier. In all events, it would be good practice to install isolation valves if the Tarm did not come with the valves (ball valves with a small stem that can be turned with a pliers or wrench).

 

[chuck172]

Are you sure you don't have the three port valves on the termovar Eric? Most of us never knew about them until it was mentioned here on this forum.

 

[hoth2oguy]

The isolation valves are located within the tailpiece included in the Termovar valve kit. The only thing showing are small nubs to turn the valves (no handles). And yes, these valves should be used for service only, not balancing.

If I understand your situation Than, this is a brand new set up and so the storage tanks are stone cold. If so, then it will take a LONG time to bring those tanks up to temperature and it will certainly seem like the water is just short circuiting back through the Termovar. You see, the water coming back to the boiler from the tanks is so cold that the Termovar is only allowing a trickle to pass through port two in order to maintain 140 degree return temperature. Therefore the flow out to your tanks - and back from your tanks - will be very small. Once the tank temperature reaches about 100 degrees F, you will start to see the Termovar open port two, allow more flow and bring the tank temp up much more quickly.

A couple of options: just hang in there and wait for the tanks to come up to temperature; or, pull the Termovar element in order to bring the tanks up more quickly. With the second option you will likely see lots of condensation in your boiler, so this is strictly a one time deal for initial commissioning. Once things are up to temperature replace the Termovar element and, because the tank temps will normally be above 100F, the problem should not come up again.

hope this helps,

Chris

Dealer Coordinator
BioHeatUSA

 

[jebatty]

pull the Termovar element in order to bring the tanks up more quickly. With the second option you will likely see lots of condensation in your boiler, so this is strictly a one time deal for initial commissioning.

This second option cannot save any material amount of time. Disregarding the potential damage to the boiler and the damage from condensation, boiler output in both options is the same. The first option puts priority on bringing the boiler itself up to temp, maintaining that temp and then diverting all excess hot water to the storage.

The second option dilutes the heat output (which is the same output as in option one) throughout the boiler + system, with potential adverse effects to the boiler and from condensation by continuing to return cold water to the boiler.

I recommend leaving the Termovar in place. If you want to see what is happening to get some peace of mind, buy some inexpensive meat probe thermometers, fasten them to 1) boiler input to Termovar, 2) boiler input to system (storage), 3) Termovar return to boiler, and 4) system return to Termovar. Wrap with insulation for more accurate readings. You likely will find the following (subject to thermometer variability):

On cold start-up, 1, 2 and 3 will gradually rise as boiler comes up to temp, but 3 may lag some in the rise as some return water is admitted through the Termovar, and 4 will continue to read cold. As boiler temp exceeds 140, 1 and 2 will continue to rise and read about the same, 3 will continue to rise to about 140 (depending on the Termovar) and stay at the reading, 4 will continue to read cold until all of the system starts to rise in temp.

As the burn continues and boiler temp rises above 140, the Termovar will continue to divert boiler hot water output directly back to the boiler and 3 will continue to read about 140 but all additional hot water will be diverted to the system. As the system itself rises in temp, 4 will start to rise. As 4 rises (above about 100-120) 3 also will begin to rise above 140 and continue to about 160. 3 will stay at 160 and 4 will continue to rise until it also reaches 160.

When 4 is at 160, the Termovar is diverting essentially all hot water to the system and none to return. 1 and 2 will continue to read the same (boiler output temp) and 3 and 4 will read the same (return from system > 160).

Again, pulling the Termovar will accomplish nothing material to bring your cold system up to temp, and in fact may or will cause avoidable damage.

 

[nporter]

Well we have had luck getting the system up to temp. Thanks to you all for this resource that one can read when one is questioning or at a loss. The installer did not install separate isolation valves around the Thermovar so we adjusted the small stubby valve controls on the Thermovar itself. The incoming port from the heating loop was set at 45° angle and that seemed to get things working. There also was an issue with an AutoMag valve that was not working. With that replaced things were much happier.

I light of Chris' mention of not using the Thermovar control for balancing, just servicing, should I set the small stubby valve controls on the Thermovar itself back to "open" now that things are working better?

Thank you Jim for the "meat probe positioning system" description. I will see about getting a case of those and tape them in the appropriate locations.

Thanks for all the information and keep the wood coming.

 

[jebatty]

I would likely use the Termovar valve for balancing until a balancing valve can be installed. You only balance boiler input into the Termovar, not system return to Termovar or Termovar return to boiler. Those latter two valves remain wide open.

 

[nporter]

Great I will see about getting a balancing valve installed on the one input in the near future.

Thanks Jim!