I have a Bosch Aquastar GWH 2400 CTD EFS LP is there a conversion kit to convert it to NG?

Stupid me but could you be a little bit literate in asking a question.

My dog write better questions that I can understand than this scribbling.

A GWH 2400 is the little brother of the GWH 2700 much like the 635ES. If you have an LP model be sure to use the overpressure protection valve supplied by Bosch as overpressure in LP (above 10-14" WC) can completely destroy this unit.

And you can use a TPR or PRV for 170,000+BTU being sure you get a House Pressure valve of 60-80-100 PSI+ and not the boiler PRV for 30 PSI

Beyond that your questions above states nothing recognizable as a technical question

I don't have good news.
You are attempting a conversion that local technicians are refusing to do.
There is a reason why we service guys steer clear of some things: liability and continual problems afterward.

Contact Bosch and find the service bulletin for that procedure.
After all this is a highly technical and finicky machine hooked to a gas line located in proximity to people.
http://waterheatertimer.org/Troubleshoot-Bosch-Tankless-water-heater.html

If this procedure is going to cost more than $400-600, and remember there is a risk it will not work afterward or will be a continual problem, then consider installing tank-type LP water heater from local box store. I recommend this.
http://waterheatertimer.org/How-to-install-gas-water-heater.html

For others in same situation: NG to LP conversions are not supported or recommended by every manufacturer. This applies to tank and tankless.
Also check there is a qualified service technician in your area before installing tankless.
Read the manual before buying.
Tankless gas savings are $1-8 per month, but all costs are energy.
Tankless cannot be exposed to more than 11 grains hardness in the water.
Tankless are maintenance heavy, and with expected repairs, maintenance and cost of parts, cost of machine and replacement cost, a simple tank-type water heater is cheaper by far.

Upvote the help.
And take advantage of fixya expert assistance live.
For a price, expert works with you while you work on water heater or any do-it-yourself project.
Fixya is always less expensive than a service call.

Before calling service technician, open following link to download typical manual, get Bosch contact information etc.
http://waterheatertimer.org/Troubleshoot-Bosch-Tankless-water-heater.html

Add a comment with your experience so others with same-similar problem can benefit.

Also take advantage of fixya expert assistance live.
For a price, expert works with you while you work on water heater or any do-it-yourself project.
Fixya is always less expensive than a service call.

A lot of factors, internal and external, can cause this problem ranging from bad PC board to plumbing problem.

Since you have no error code, it could be plumbing,
http://waterheatertimer.org/pdf/No-Error-Code.pdf

Open following link for useful Bosch troubleshooting information including Bosch support and typical manual for 2700 gas tankless:
http://waterheatertimer.org/Troubleshoot-Bosch-Tankless-water-heater.html

For folks with Rheem tankless:
http://waterheatertimer.org/Troubleshoot-Rheem-Tankless-water-heater.html

Add a comment with your experience so others with same-similar problem can benefit.

Also take advantage of fixya expert assistance live.
For a price, expert works with you while you work on water heater or any do-it-yourself project.
Fixya is always less expensive than a service call.

Call qualified service technician, and ask that person questions about maintenance and tips.
Then keep service technician number in rolodex-wallet.

Resourceful do-it-yourselfer will find following links handy.
Tankless are maintenance heavy, and Bosch and Rheem etc say to call service technician for recurring problems. Especially when short-hand troubleshoot section doesn't solve problem.
People spend years learning how to service tankless.

Bosch has online tech support form:
http://forms.boschhotwater.com/Home/BoschTechSupportForm/tabid/614/Default.aspx

BOSCH error codes online:
http://www.boschhotwater.com/HelpfulResources/TechnicalSupport/BoschAquaStarModels/2400ESTechSupport/Troubleshooting/tabid/1295/Default.aspx

Bosch manuals:
http://www.boschhotwater.com/HelpfulResources/BrochuresManuals/tabid/354/Default.aspx

Bosch problems at Fixya:
Open following links and read about tankless problems to understand the field and glean useful information.
http://www.fixya.com/support/p949576-bosch_1600h_lp_liquid_propane_aquastar_a/solutions

Install DIY tank-type gas water heater and avoid the whole headache
http://waterheatertimer.org/How-to-install-gas-water-heater.html

Post question on pro water heater forum: This is where I go to catch up on latest info in always-evolving water heater industry.
http://www.thetankatwaterheaterrescue.com/forums/forum3/

Pay for an answer at fixya:
Also take advantage of fixya expert assistance live.
For a price, expert works with you while you work on water heater or any do-it-yourself project.
Fixya is always less expensive than a service call.

Problem could be air supply, gas supply, venting, part failure or combination of listed things.

Best place to start is manual.
http://www.boschhotwater.com/BoschModel1600H/FeaturesandSpecs/tabid/1024/Default.aspx

Typical 1600 manual shows troubleshoot starting page 19
http://www.boschhotwater.com/Portals/7/TechManuals/1600H_English_0606.pdf

Bosch has online tech support form:
http://forms.boschhotwater.com/Home/BoschTechSupportForm/tabid/614/Default.aspx

BOSCH error codes:
http://www.boschhotwater.com/HelpfulResources/TechnicalSupport/BoschAquaStarModels/2400ESTechSupport/Troubleshooting/tabid/1295/Default.aspx

Add a comment for more free help.
Also take advantage of fixya expert assistance live.
For a price, expert works with you while you work on water heater or any do-it-yourself project.
Fixya is always less expensive than a service call.

No kits are available to convert his unit to NG. This is because the LP uses copper pipe and is within code, the NG uses black pipe and each unit is specifically designed, entirely, to use the gas associated with the unit.

I was looking for a service manual, which you apparently do not supply. I was not looking for someone who will charge me a fee to get information. I can get that info directly from Bosch for free. Thank you for answering. John

BOSH AQ 250 On demand propane water heater ran out of propane, got gas now, but get EC flashing on the display and the unit won't fire? Lost manual, any suggestions. Thanks, Jim

yes you can buy a con/kit expert job dont tackle