New input on my system -no heat exchangers with OWB??

[headrc]

I have received some input on my system design from somoen who has designed systems before. I am planning on using an OWB as my heat source for my system and plan on doing radiant heating . I was led to believe previously that because the OWB is an open loop design that I would need to put all secondary loops on heat exchangers in order to separate pumps etc. from it and to also be able to pressurize those loops. A person very familiar with these system designs has just advised me otherwise. He stated that if he designed the system he would not do it that way. He advises keeping it an open loop system and using stainless steel or bronze pumps etc.. His argument is the savings in heat exchangers and their required maintenance will offset the higher cost of the the stainless steel or bronze circulators and that it will be a simpler system to design and maintain. Does anyone have any input on this concept? Thx again, RH

 

[WoodNotOil]

I am no expert by a long shot, but I think that pressure in a hydronic heating system has to do with having enough pressure to lift the water to the highest point in the system to reach radiators. If you are only using radiant heat in floors, then you may be able to run it at the lower pressure level that your boiler is at. Hopefully one of the pros here will hop in on this one. The person you talked to is probably right in this case.

 

[Red Sun]

We do not recommend or support open-loop heating systems.


Why?

The low temperatures of a radiant floor system can become a breeding ground for potentially fatal bacteria. This opinion is based upon our experience along with National, state and university studies and warnings. This is what some sources say about safe potable water temperatures.

http://www.houseneeds.com/shop/heat...sp?stype=atop/radiantheatingindex.asp&level=2

 

[deerefanatic]

yes, but he's not drinking the stuff... Just not capping it off and putting a pressure tank on it........

I say go for it just so long as you can get it purged........

 

[headrc]

That is correct of course ..this will not be potable water. What kind of challenges do I have about purging the system without it being pressurized? RH

 

[deerefanatic]

Well, if it's unpressurized and there is a point in the system higher than your fill point...... well....... lets just say water doesn't run uphill very well.

 

[headrc]

Got it ....and I do have an upstairs in the house that could be higher than the fill point ....although the OWB (which will most probably be the fill point with this design) will be on a higher grade than the house ...so I will have to check that out. Any ideas if this does present a problem ....other than going to the heat exchangers and pressurizing etc. Thx, RH

 

[deerefanatic]

Not much that can be done....... The laws of gravity are sometimes against us all! You can make a set of isolation ball valves and power-fill it with well water pressure, then unisolate to reconnect to the rest of the system.... but it would be a pain because one little bubble of air could airlock that whole zone and leave you needing to power-purge it again....

 

[mtfallsmikey]

Easist way is to use check valves at the OWB (Taco IFC has them built in)...use an HX

 

[headrc]

Well ...again I was planning on using heat exhanger(s) but was advised not to ....from someone who designs systems professionally. Another reason he gave is that heat exchangers need to be cleaned and maintained yearly ....which I did not know this. So I am still undecided here ....that is what I needed ...more choices! RH

 

[mtfallsmikey]

Use Y-strainers in all supply lines........