How JustAnswer Works:

  • Ask an Expert
    Experts are full of valuable knowledge and are ready to help with any question. Credentials confirmed by a Fortune 500 verification firm.
  • Get a Professional Answer
    Via email, text message, or notification as you wait on our site.
    Ask follow up questions if you need to.
  • 100% Satisfaction Guarantee
    Rate the answer you receive.

Ask Jerry Your Own Question

Jerry
Jerry, HVAC Technician
Category: HVAC
Satisfied Customers: 422
Experience:  Epa universal certification, hearth products specialized.
34748161
Type Your HVAC Question Here...
Jerry is online now

Everything functions when first fired up but hot water to heating

Customer Question

Everything functions when first fired up but hot water to heating system does not circulate. Only get one cycle before (overheat?) shutdown, boiler just sits with demand light running. Grundfos pump is working, have checked impeller, tight on shaft and not blocked up. All radiators have been bled. Is it possible/probable that there could be an airlock elsewhere in the system? Hot water is fine throughout the house. Any clues would be helpful thanks.
Submitted: 3 years ago.
Category: HVAC
Expert:  Andrew Smith replied 3 years ago.
Have you had the plug out of the pump when the system is one just to make sure the pump is spinning?
Customer: replied 3 years ago.
Yes, it runs at hi speed lo speed and switches off on its on board switch.
Expert:  Andrew Smith replied 3 years ago.
It could be, are you getting heat from the boiler (trace the pipework from the boiler and see how far it goes?)
Customer: replied 3 years ago.
Heat exchanger runs initially and heats water along approx fifteen inches of pipe towards a 90 degree downward bend. (This boiler is in the roofspace of the house to simplify pipe work and has been running ok for years). Presumably because something is preventing circulation the heat exchanger shuts down when water temp too high. All rads bled three times no air pockets, what else can prevent circulation??
Expert:  Andrew Smith replied 3 years ago.
If the pump was running correctly I would expect much more circulaion, is there a speed selector on the top?
Customer: replied 3 years ago.

I think i already answered that!!!

Expert:  Andrew Smith replied 3 years ago.
The pump should run at a constant speed, is it not the fan that runs at 2 different speeds?
Customer: replied 3 years ago.

Pump seems to run at constant speed . It has three switch settings, Off, low speed and high speed. it is set at high speed and always has been. I have no way of knowing if the speed currently is correct to the manufacturers spec.

Expert:  Andrew Smith replied 3 years ago.
With the cover off, can you tell if it is the fan that is changing speed?

What Customers are Saying:

 
 
 
  • You did one super job of explaining to me everything there is to know about this fridge. I'm looking forward to asking you questions in the future. Jimmy
< Previous | Next >
  • You did one super job of explaining to me everything there is to know about this fridge. I'm looking forward to asking you questions in the future. Jimmy
  • Wonderful service, prompt, efficient, and accurate. Couldn't have asked for more. I cannot thank you enough for your help. Mary C.
  • This expert is wonderful. They truly know what they are talking about, and they actually care about you. They really helped put my nerves at ease. Thank you so much!!!! Alex
  • Thank you for all your help. It is nice to know that this service is here for people like myself, who need answers fast and are not sure who to consult. GP
  • I couldn't be more satisfied! This is the site I will always come to when I need a second opinion. Justin
  • Just let me say that this encounter has been entirely professional and most helpful. I liked that I could ask additional questions and get answered in a very short turn around. Esther
  • Wonderful service, prompt, efficient, and accurate. Couldn't have asked for more. I cannot thank you enough for your help. Mary C.
 
 
 

Meet The Experts:

 
 
 
  • theplumber717

    theplumber717

    HVAC Technician

    Satisfied Customers:

    153
    Lic plumbing and heating contractor, 28 years exp
< Last | Next >
  • http://ww2.justanswer.com/uploads/TH/theplumber717/2011-11-24_34039_DSCF7012.64x64.JPG theplumber717's Avatar

    theplumber717

    HVAC Technician

    Satisfied Customers:

    153
    Lic plumbing and heating contractor, 28 years exp
  • http://ww2.justanswer.com/uploads/BI/billyjr1961/2013-9-27_11122_ATT1351123267229photo.64x64.JPG Billy's Avatar

    Billy

    HVAC Technician

    Satisfied Customers:

    9124
    Journeyman Heating/Cooling Technician.
  • /img/opt/shirt.png Brian's Avatar

    Brian

    HVAC Technician

    Satisfied Customers:

    53
    OFTEC registered oil heating engineer and plumber.
  • http://ww2.justanswer.com/uploads/PL/Plumberpro/2014-6-23_6520_image.64x64.jpg Plumberpro's Avatar

    Plumberpro

    Plumber

    Satisfied Customers:

    40
    Fully qualified plumbing , heating and gas engineer 20 years experience
  • http://ww2.justanswer.com/uploads/MA/MarkAYng/2011-1-15_16358_Markcameo2008b.64x64.jpg MarkAYng's Avatar

    MarkAYng

    Handyman

    Satisfied Customers:

    0
    Knowledgeable in home, electrical and small appliance repair.
  • http://ww2.justanswer.com/uploads/AS/AssuredElectrical/2011-9-13_221243_me.64x64.gif AssuredElectrical's Avatar

    AssuredElectrical

    Home Improvement Enthusiast

    Satisfied Customers:

    332
    Electrical contractor's license
 
 
 

Related HVAC Questions