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 Andrew Smith Your Own Question

Andrew Smith
Andrew Smith, Engineer
Category: UK Plumbing
Satisfied Customers: 3125
Experience:  Domestic Gas, Commercial Gas, LPG, Unvented Hot Water, Part P Electrical, Commercial Catering
46681511
Type Your UK Plumbing Question Here...
Andrew Smith is online now
A new question is answered every 9 seconds

when I run the hot water the system pressure drops and hot

Customer Question

when I run the hot water the system pressure drops and hot water does not reach temerature .Could this be a fault on the differential valve DHW ?
Submitted: 3 years ago.
Category: UK Plumbing
Expert:  Rick Ridley replied 3 years ago.
Hi I am Rick, UK Plumber, and I specialize on Boiler problems, need a little more info to say, is this a combi boiler or an unvented cylinder, Rick
Customer: replied 3 years ago.
Hi Rick it is a Baxi Combi Instant 105e
Expert:  Rick Ridley replied 3 years ago.
OK when you run hot water you say the system pressure drops is that correct? can you say what the pressure is before and during running hot water, Rick
Customer: replied 3 years ago.
when running the hot water the system pressure drops from just over 1 bar to practically 0 this is not a sudden dramatic drop but over a period of a few minuets and then the system requires topping up
Expert:  Andrew Smith replied 3 years ago.
Hi my name is XXXXX XXXXX lets see if we can get you sorted in the shortest possible time. Your plate to plate heat exchanger could be blocked? Can you check whether the pressure relief valve (15mm copper pipe going through the wall to outside below the boiler) is dripping or running outside? Has this been getting gradually worse?
Customer: replied 3 years ago.
No this is dry
Expert:  Andrew Smith replied 3 years ago.
If the boiler is not discharging outside, then you will have a leak. Do you have any damp patches anywhere?
Customer: replied 3 years ago.
no no damp patches point to note that if heating is on then the pressure is fine this only happens when drawing hot water
Expert:  Andrew Smith replied 3 years ago.
If on heating does the pressure go back up again? Depending on the model and where the pressure gauge is connected into the boiler, if there is a slight restriction in the plate to plate heat exchanger the pressure from the pump can make the system pressure in the boiler decrease.
Customer: replied 3 years ago.
no I have to recharge the system
Expert:  Andrew Smith replied 3 years ago.
There is only two ways for water to leave the system - a leak or it blows out the PRV. I would encourage some investigation, under floorboards etc.
Andrew Smith, Engineer
Category: UK Plumbing
Satisfied Customers: 3125
Experience: Domestic Gas, Commercial Gas, LPG, Unvented Hot Water, Part P Electrical, Commercial Catering
Andrew Smith and other UK Plumbing Specialists are ready to help you

JustAnswer in the News:

 
 
 
Ask-a-doc Web sites: If you've got a quick question, you can try to get an answer from sites that say they have various specialists on hand to give quick answers... Justanswer.com.
JustAnswer.com...has seen a spike since October in legal questions from readers about layoffs, unemployment and severance.
Web sites like justanswer.com/legal
...leave nothing to chance.
Traffic on JustAnswer rose 14 percent...and had nearly 400,000 page views in 30 days...inquiries related to stress, high blood pressure, drinking and heart pain jumped 33 percent.
Tory Johnson, GMA Workplace Contributor, discusses work-from-home jobs, such as JustAnswer in which verified Experts answer people’s questions.
I will tell you that...the things you have to go through to be an Expert are quite rigorous.
 
 
 

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 Bagley, IA
< Last | 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 Bagley, IA
  • Wonderful service, prompt, efficient, and accurate. Couldn't have asked for more. I cannot thank you enough for your help. Mary C. Freshfield, Liverpool, UK
  • 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 Los Angeles, CA
  • 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 Hesperia, CA
  • I couldn't be more satisfied! This is the site I will always come to when I need a second opinion. Justin Kernersville, NC
  • 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 Woodstock, NY
  • Thank you so much for taking your time and knowledge to support my concerns. Not only did you answer my questions, you even took it a step further with replying with more pertinent information I needed to know. Robin Elkton, Maryland
 
 
 

Meet The Experts:

 
 
 
  • Rick Ridley

    UK Heating Engineer

    Satisfied Customers:

    1559
    30 Years on the tools, now retired, Ex CORGI
< Last | Next >
  • http://ww2.justanswer.com/uploads/solarman1947/2009-12-13_223915_phpkKBcXq_c2PM.jpg Rick Ridley's Avatar

    Rick Ridley

    UK Heating Engineer

    Satisfied Customers:

    1559
    30 Years on the tools, now retired, Ex CORGI
  • http://ww2.justanswer.com/uploads/CH/chamberlains/2011-6-11_181053_Photoon20110611at19.06.64x64.jpg Chamberlain Maintenance's Avatar

    Chamberlain Maintenance

    Plumber

    Satisfied Customers:

    310
    Qualified Plumber with over 17 years experience in Domestic & Commercial plumbing.
  • http://ww2.justanswer.com/uploads/QW/qwasert/2011-11-24_221527_ben.64x64.JPG qwasert's Avatar

    qwasert

    Plumber

    Satisfied Customers:

    187
    Condensing and Combi Boilers
  • http://ww2.justanswer.com/uploads/VE/Veillplumb/2011-8-31_155028_IMG1104.64x64.JPG Marc's Avatar

    Marc

    Plumber

    Satisfied Customers:

    122
    Plumbing and Heating expert with 25+ years experience, 21+yrs self employed as a contractor.
  • http://ww2.justanswer.com/uploads/JA/JACUSTOMER4xr7932a/2011-11-12_2244_SmallFacePhoto.64x64.jpg Ardent Engineering's Avatar

    Ardent Engineering

    Engineer

    Satisfied Customers:

    49
    Registered Gas Installer
  • http://ww2.justanswer.com/uploads/DA/DanRobinson/2012-5-13_221341_Me.64x64.JPG Dan_Robinson's Avatar

    Dan_Robinson

    Plumber

    Satisfied Customers:

    33
    Owner and Director of Jennings Heating Ltd. Registered to work with Gas and High pressure hot water systems.
  • /img/opt/shirt.png Brian's Avatar

    Brian

    Plumber

    Satisfied Customers:

    400
    16 yrs. experience as plumber, including full bathroom and kitchen installations.
 
 
 

Related UK Plumbing Questions

Chat Now With A Plumber
Andrew Smith
Andrew Smith
General Manager
2270 Satisfied Customers
Domestic Gas, Commercial Gas, LPG, Unvented Hot Water, Part P Electrical, Commercial Catering