navien ch240 hot water is working but not heating the house


  #1  
Old 12-15-17, 07:24 AM
B
Member
Thread Starter
Join Date: Dec 2017
Location: United States
Posts: 10
Upvotes: 0
Received 1 Upvote on 1 Post
navien ch240 hot water is working but not heating the house

The problem started this morning / last night. I'm still getting hot water on the DHW side but not getting any hot air from my air handler.

The pipes that go to the air handler are cold to touch, I suspect the hot water isn't circulating? However there is no error code, if the circulation pump is toasted I should be getting an error code? Puzzling...
 
TheRandyMan voted this post useful.
  #2  
Old 12-15-17, 10:02 AM
PJmax's Avatar
Group Moderator
Join Date: Oct 2012
Location: Jersey
Posts: 64,939
Received 3,952 Upvotes on 3,545 Posts
Welcome to the forums.

There's only one circulator. If it's not running you won't get hot water anywhere. That unit uses a 3 way valve to control water flow from DHW to the heating loop. It appears it may be stuck. In the service manual link below on page 51..... the valve and diagnosis is illustrated.

Navien_CH_Service_Manual.pdf
 
  #3  
Old 12-15-17, 10:09 AM
B
Member
Thread Starter
Join Date: Dec 2017
Location: United States
Posts: 10
Upvotes: 0
Received 1 Upvote on 1 Post
yeah thanks i was researching more and thinking the valve is probably not working.
so i just need to get a new valve and replace it?
i looked at the service procedure seems DIY'able... i just have to drain the unit (from the 2 drain valves) before i do it?
 
  #4  
Old 12-15-17, 10:16 AM
PJmax's Avatar
Group Moderator
Join Date: Oct 2012
Location: Jersey
Posts: 64,939
Received 3,952 Upvotes on 3,545 Posts
I don't replace parts without checking first. There is no way of knowing if it's electrically or mechanically the valve or if it's just not getting power from the board.
 
  #5  
Old 12-15-17, 06:51 PM
B
Member
Thread Starter
Join Date: Dec 2017
Location: United States
Posts: 10
Upvotes: 0
Received 1 Upvote on 1 Post
given that it sits all the way back there, i can't really get hold of the wire and check the voltage... would you have some suggestion on how to check it without taking out the PCB and pump out?
 
  #6  
Old 12-15-17, 08:28 PM
PJmax's Avatar
Group Moderator
Join Date: Oct 2012
Location: Jersey
Posts: 64,939
Received 3,952 Upvotes on 3,545 Posts
These are not easy units to work and they are not DIY friendly. I only work on an occasional tankless heater. This is not my specialty.

On page 110 of the manual it talks about a possible clogged filter when "no space heating when the boiler is running." Filter checking/cleaning on page 135.

I was thinking that it could also be a circulator pump problem because that pump is not used for domestic water.... only space heating Page 88 describes checking pump.

The voltages you need to check should be available on the control board.
They are on the black and blue wires on plug M. It can be found on page 30.
 
  #7  
Old 12-18-17, 10:33 AM
B
Member
Thread Starter
Join Date: Dec 2017
Location: United States
Posts: 10
Upvotes: 0
Received 1 Upvote on 1 Post
Thanks for all your tip Pete.

I know these units are pain in the ass when things broke in them.

Latest development - over the weekend the situation switched... now we have heating but no hot water. I'm pretty convinced it is a valve problem now given we're getting hot water on either side. (if it's the circ pump or filter it won't be possible for us to get space heating now). I guess over the weekend somehow the valve managed to unstuck itself once and switch position from DWH to space heating so now it's stuck at space heating.

I have ordered a replacement valve, will try to replace it myself this afternoon when it arrive... wish me luck!
 
  #8  
Old 12-19-17, 03:00 PM
B
Member
Thread Starter
Join Date: Dec 2017
Location: United States
Posts: 10
Upvotes: 0
Received 1 Upvote on 1 Post
fyi pete i replaced the valve it's now working like a charm. thanks for pointing me at the right direction!
 
  #9  
Old 12-19-17, 03:23 PM
PJmax's Avatar
Group Moderator
Join Date: Oct 2012
Location: Jersey
Posts: 64,939
Received 3,952 Upvotes on 3,545 Posts
Great news. Thanks for letting me know how you made out.
 
 

Thread Tools
Search this Thread
 
Ask a Question
Question Title:
Description:
Your question will be posted in: