When were the burners last cleaned? did any check for spilage (down drafts)?

thank-you for the response....I do not believe the burners have been cleaned. The tank is 7yrs. old, with us recently moving into this residence.The burner have very little orange color ...if any, when in full flare, and I cannot honestly respond to the down draft.

Does a thermo-coupler need replacing?

thank again

The thermocouple just maintains pilot light If the pilot light does not stay on then it need replacemsnt BUT a 7 year old heater I personally would just replace the entire heater

thank-you, i failed to mention, that this tank is used for under floor heating, which i have never used yet.

I appreciated your feedback. Thank-you

Your very welcome