Rinnai Instance hots On Trane units.

[CASINOREFER]

Having some problems with these units keeping the loop at 180deg.
There is 4 of them on a 50ton Trane, with 100%OSA. They are rated at 200,000BTUs. Designed to 15deg OSA, DAT of 80deg. Have checked water flow at each heater, they range from 2.3GPM to 8.5GPM. Have pulled screens out of them and clean them, hardly any change, disconnected water modulating valve [in each heater ]still no change, have started unit in service mode, at this point they should be wide open, yet water flows are still not high. Have checked other units there water flows at start-up are in the 7.5 range. Checked this unit this AM. OSA35deg,water in @153, out-107deg,dischair @59deg.
Trane service has looked at this, no answer on water flow,Rinnai has not yet come up with any thing new.

[jayguy]

your water delta T is 46F

1. at 2.3 gpm = 53,000 btuh, not getting the 200k
2. at 7.5 gpm = 173,000 btuh, close to 200k
3. at 8.5 gpm = 196,000 btuh, very close to 200k

if you are running 8.5 gpm in your last reading, then you are getting the proper amount of heat out of the water and this is probably not the problem. could be low heat transfer (dirty coils, high air flow, etc) if you are running 7.5 gpm in your last reading, then same as 8.5 gpm issue but you could have a small problem with the water. if you are running the 2.3 gpm, then it is obviously the problem. 46F delta T in your water seems high (like low water flow)

[Moose]

Did it ever work @ the OAT you have now?

[CASINOREFER]

No

[vmc1161]

inlet and outlet right?

[CASINOREFER]

Jayguy: Coils clean, filters ok, units 4mos old. Don't have much experience with these Rinnai units. Trane didn't install any gauges on these systems, don't even know how much water they take ,you woulda thought they would give some stats or info, no petes plugs. Trying to keep from not voiding the warranty.
This is a new heating system for Trane, I have not heard or seen these before.

[jayguy]

i helped install one that was an 8 zone system on LP gas about 1.5 years ago. after we got the airflow right (that took forever!) we had no problems. the way Rinnai heats water may be a little different, but they have to obey mother nature too. it is difficult to be able to tell what you should have...i would get the submittal (if its only 4 months old, it should be pretty easy). the submittal will have design pressures, temperatures and flow rates (even if you can not measure them). its a starting point. when i run into problems like this, that i may not be able to fully understand, i get the submittal and try to get the unit to run to those pressures and temperatures. if it still does not work, that's the engineers issue.

[CASINOREFER]

jayguy: The submitals sound like a good Idea. I have a meeting with Trane Sales Tomorrow, I will ask then and throw this mess in their lap, to solve.
Thanks

[jayguy]

be careful. the way to work with an engineer is to overload them with numbers. they will probably dismiss you (because you are not an engineer!), but they can not overlook a bunch of numbers (its like crack to them:D ) be prepared to be told that the problem is with the one thing that you did not measure...just stay on it.

good luck.