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Burnham k2 combi - takes long time for hot water

Jiggs1219Jiggs1219 Posts: 2Member
edited September 2019 in Domestic Hot Water
Hey guys,

Just converted to gas and have this unit. Every time there is a call for hot water, the combi unit goes through a series of tests before the unit fires off and starts producing hot water. This happens every time and we have to wait 3 to 4 mins for hot water. It seems it goes thru a procedure where it runs a series of tests before giving the OK to turn on the flame. This is very annoying as you can imagine and wife is not happy. The plumber who converted called Burnham and they told him that’s normal. They said according to him that’s it’s setup fine and that there isint a way to turn off 45 second to a minute of tests. I find that hard to believe because it’s just not practical. I have heard of waiting for hot water. 30-45 seconds but not 3 mins. Somehow is there a way to bypass the procedure? I don’t know if anyone knows what I’m talking about but maybe someone with this unit or has experience with this unit knows what I am talking about. Please help. Our next option is to buy a separate hot water tank. Thanks.


  • Jiggs1219Jiggs1219 Posts: 2Member
    Can anyone help? Thinking of getting a 30 gallon electric water heater to fix this. Was hoping not to :(
  • Jamie HallJamie Hall Posts: 12,137Member
    No one is helping, likely because if you have a large (and a combi is large) gas fired appliance it is going to go through a self test before it lights off. This is a safety issue. The length of the self test and purge varies somewhat with manufacturer, but 45 seconds doesn't sound unreasonable.

    The remainder of the delay is likely to be the length of time it takes the unit up to temperature and the length of time it takes the now hot water to get to your tap. 20 feet of half inch pipe has -- roughly -- a gallon of water in it; with some low flow shower heads, for instance, it may take a minute just to empty the cold water out of a 20 foot pipe.
    Br. Jamie, osb

    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England.

    Hoffman Equipped System (all original except boiler), Weil-Mclain 580, 2.75 gph Carlin, Vapourstat 0.5 -- 6.0 ounces per square inch
  • mikeg2015mikeg2015 Posts: 1,126Member
    Some combi’s are faster at switching and their internal heat exchanger stores some heat on initial startup.

    In your case, seems like it needs a small electric as a buffer tank.

    Really wont cost much to operate your only heating that first 1 minute of water flow. Probably 10-20% of your total hot water use. Most water use are longer draws for showers, tubs, dishwasher and clothes washer.

    You can also store it at 140F and use a mixing valve for more stable temperatures.
  • windsor454windsor454 Posts: 1Member
    I was wondering is the hot water issue has been resolved. We had a Burnham K2 combi installed end of December to replace old boiler and water heater. Heat works great. But the hot water is inconsistent and I haven't discovered a pattern. During showers the water cycles hot to cold/cool back to hot several times before steady hot. Really annoying. Today at a sink in laundry room close to boiler the water started hot then went cold and did not cycle back to hot. Other times it's fine and no shower cycling. A Burnham rep is supposed to come tomorrow. I haven't paid the balance yet because if they can't get us consistent hot water I want to have some recourse. Don't know if the unit is defective or if the system was sold to us overrated but underwhelming.
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