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 Dales-Electronic Your Own Question
Dales-Electronic
Dales-Electronic, HVAC Technician
Category: HVAC
Satisfied Customers: 1464
Experience:  I am a Home Appliance / Refrigeration Technician of 25yrs+ with my own business and for multi-brand national companies.
26760916
Type Your HVAC Question Here...
Dales-Electronic is online now

Why is it that my combi-boiler heats the water perfectly for

Resolved Question:

Why is it that my combi-boiler heats the water perfectly for the sink in my bathroom, but the shower water is tepid? I've had the pin thingy changed and a new heat plate - but all my plumber says is that Combi boilers will only heat to so many degrees above outside temperature - but this is disproved by the basin hot tap which is toasty!! The shower is brand new - so no limescale.
Submitted: 2 years ago.
Category: HVAC
Expert:  Dales-Electronic replied 2 years ago.
Dales-Electronic :

OK my name is ***** ***** I will attempt to solve this problem for you, can you advise me what the manufacturer of the boiler is and also its model number and also the shower manufacturer.

Dales-Electronic :

Ready to go when you have supplied the above ~ Ian

Customer:

Hi Ian,

Customer:

HRM Wallstar boiler Serial No. 20/02508 - 25/19:20 Shower I bought recently from Wickes - a simple set height large head

Dales-Electronic :

OK just a little more information, when we are talking about the shower head how is it connected to the water services ?

Customer:

Its plumbed in to hot and cold pipes which have a long run from the boiler - I've had them lagged thinking that would help, but still can't understand how sink tap is hot and shower is not?

Dales-Electronic :

Approx how long is the run?

Customer:

Maybe 50 feet or so?

Customer:

I've tried taking shower head off but no difference and I've tried running the cold tap in the basin at the same time which does help a little.

Dales-Electronic :

OK you will have to leave this with me but I need more information if you can give it, I need specific details of the boiler as I cant find the 25/19 wallstar on their page. I assume it is oil fired but correct me if its gas, however from what I can see you should be getting somewhere around 35C at the shower head which is a lot hotter than tepid. I could also use the size of the supply pipes to the shower head.~ The information that I have here also refers to mixing valve below the boiler which can be changed from 1 to 5 to increase/reduce the temperature of the hot water ~ Ian

Customer:

Yes it is oil fired Ian - I have the handbook in front of me. The mixing valve is on 5.

Dales-Electronic :

OK can you give me what is on the front of the handbook and I will contact wallstar for you tomorrow and have a chat about this problem, it surely seems strange to me, I have a combi boiler here at home and whilst the run is only about 30 feet it give a belting hot shower, with out lagging. OK I have to let it run for about 5 minutes to get the pipes warm but once they're up to temperature its fantastic. I usually have a shave whilst Im waiting ~ Ian

Dales-Electronic :

Can you confirm that the shower pipes are connected to the same supply as the basin ?

Customer:

Ok - supply pipes are about an inch. The only information on the front of the handbook is HRM Wallstar Boiler Service no. 20/02508 - 25/19:20

Customer:

Yes the shower pipes are the same supply as the basin - and yes I do let the shower run for about five minutes like you say. Look forward to hearing from you. Thanks, Julie

Dales-Electronic :

OK leave it with me will find out and see what they suggest and come back to you tomorrow ~ Ian

Customer:

Ok thanks

Dales-Electronic :

OK I have an answer of sorts from Wallstar when you are ready to go ~ Ian

Customer: Hi Ian sorry to keep missing you - busy time of year! Will go online tomorrow - what's best time? Julie
Dales-Electronic :

OK Im here if you want the information

Dales-Electronic :

OK I'm on here from 1600 tomorrow ~ Ian

Customer:

Yes I'd still like the information please. Will try and catch you online over the next few days. Julie

Dales-Electronic :

OK are you still here I am online

Customer:

Hi yes

Dales-Electronic :

OK bearing in mind what you told me earlier about the pipes to the shower being about 1 inch (likely 22mm) I spoke to Wallstar technical on Your behalf. I was advised that the installation instructions show clearly that to achieve a 35C increase from the mains water incoming temperature that the supply pipes must not be greater in size that 15mm. Anything greater that 15 causes too much loss of heat through the extra external surface area of the pipework and they are not surprised that you cant get any decent temperature at the shower head. Not a very satisfactory answer for You but at least you have a expert Wallstar opinion ~ Ian

Customer:

Thanks for your time looking into this for me Ian - and contacting Wallstar. Still doesn't explain why the basin hot tap gets really hot? I guess I'll just have to use the shower downstairs which is closer to the boiler. Have a good Christmas. Julie

Dales-Electronic :

As I said Im sorry to be the supplier of bad news, perhaps an electric power shower for upstairs? Would you now kindly rate my advice to you so that I can close down you information request. Have a great Christmas and New Year ~ Ian

Dales-Electronic and other HVAC Specialists are ready to help you

Related HVAC Questions