I have a Rinnai tankless water heater. As fa as I can tell I have hooked it up properly to flush it, however the Rinnai will not let the vinegar run through it. The pump works, all of the valves are set properly, when I nitially turn the pump on a flush of vinegar will pulse through the system, but then that is it. The pump continues to work, but nothing further goes through the system. Is there a valve that won't let me flush? Help

Hi,
There should be no valves....was water still coming through or had the coils totally plugged up before you tried to clean them? Even so, if you were very near plugged then the vinegar will brak loose some mineral and it will plug up...try reversing the flow a number of times to see if you can establish flow through the coils. I have had to do that sometimes because people waited too long before calling for a cleaning... there has been one occasion when a coil totally plugged on me when trying to clean it and I could not get it back open and had to replace it...
Also using compressed air may get the coil open so that you can get liquid through it again....

as you are finding out this type of cleaning can be very frustrating... don't give up too soon... keep working at it...

heatman101

Hi, well if it will not allow the fluid to be pumped through, then there must be some sort of blockage, partial or similar in the unit itself. The path for either is the same? There are no other valves, this is evidenced by the fact that some does come through, if there was some sort of restriction, then none would come through at all. And you indicate that it does, but sporadicly. So you need to find the blockage and free it up, either that or the Pump is blocked or not working correctly, you will have to check that out too, the only real way to do this is by disassembly. To do this you need a service manual, either Google for one, using the exact make and model, and the words service manual added. Or contact Rinnai, and ask them for a service manual, this then will enable you to troubleshoot effectively, it also has all the spare parts numbers so one can order replacement parts.
Of course if you do not wish to DIY, then get it looked at by a Rinnai agent, and ask for a "Quote" before allowing any repair work to be undertaken.