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Andrew Smith
Andrew Smith, HVAC Technician
Category: HVAC
Satisfied Customers: 3626
Experience:  City & Guilds Plumbing and Heating Engineer
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I have a baxi luna 310fi i only get hot water when i have to

Customer Question

i have a baxi luna 310fi i only get hot water when i have to fixtures open
JA: How long has this been going on? And how severe is the problem?
Customer: a month
JA: Do you plan on doing the work yourself?
Customer: yes
JA: Anything else we should know to help you best?
Customer: when i have sink hot side on it does not get hot when i turn shower and sink on at the same time water gets hot
Submitted: 7 months ago.
Category: HVAC
Customer: replied 7 months ago.
i get no hot water when i have one fixture open on sink but when i have sink on and shower on i get hot water
Expert:  Rick replied 7 months ago.

Welcome to Just Answer, my name is ***** ***** I will do my best to help you with your issue. If my initial response doesn’t answer your question then let me know and we can continue our conversation.

First check the filter on the cold water feed into the unit. If that's clean then you probably have a problem with the DHW flow valve or your flow rate out of the sink is less than 2.5 l per minute.

Customer: replied 7 months ago.
it dosent work with just the shower on
Customer: replied 7 months ago.
nothing wrong with sink
Customer: replied 7 months ago.
where is filter located
Expert:  Rick replied 7 months ago.

I didn't say there was anything wrong with either. I just indicated the minimum flow rate to activate the unit. Filter is at the cold water connection. You have to disconnect the water line to get to it.

Customer: replied 7 months ago.
its clean
Expert:  Rick replied 7 months ago.

Then you probably have an issue with the flow valve. Do you have the manual?

Customer: replied 7 months ago.
filter is clean still not workin
Expert:  Rick replied 7 months ago.

Did you see my last response??

Customer: replied 7 months ago.
no i dont have the manual
Customer: replied 7 months ago.
where is flow valve located
Expert:  Rick replied 7 months ago.

Ok here's a link to the manual. You need to follow the troubleshooting flow chart starting on page 36

http://www.designheating.com/pdf/Luna%20310%20Manual[1].pdf

Expert:  Rick replied 7 months ago.

Here's a link to an online parts supplier
http://www.parts4heating.com/category-s/6693.htm

Customer: replied 7 months ago.
do you know the part number
Expert:  Rick replied 7 months ago.

You need to follow the troubeshooting flow chart first. You don't know what part you need yet

Customer: replied 7 months ago.
what is dhw tap and where is it
Expert:  Rick replied 7 months ago.

I'm going to open this up to my colleagues so one of them can help. Please don't respond (even to acknowledge this post)until you get a response from us. If you respond first it will only delay your answer.

Expert:  Andrew Smith replied 7 months ago.
It sounds like the hot water flow switch is worn and therefore needs a higher water flow rate to trigger the boiler
Customer: replied 7 months ago.
What is the part number
Customer: replied 7 months ago.
What is part number for flow switch so I can order it
Customer: replied 7 months ago.
This is taking to long for an answer
Customer: replied 7 months ago.
All I wanna know is what is the part number
Customer: replied 7 months ago.
Why do I have to wait 24 hours or more for such a simple question
Expert:  Andrew Smith replied 7 months ago.

http://www.designheating.com/pdf/Luna%20310%20Manual%5B1%5D.pdf

Page 46 item 103 is the usual culprit