Combi boiler, hot as normal then cold! Scale? (Worcester)

[stephendill]

Hello,I hope someone can offer me some advice please?

I have a combination boiler. It id a Worcester 28i junior. I have the manual here with me.

Anyway the problem is, when hot water is on,it's great, very hot, not too long to wait, and then all of a sudden, goes cold (like normal cold water). after a min or so it goes hot again.

Now from what I have read and been told, it sounds like a scale problem. There is no scale reducer installed on the cold supply to the boiler and the water here is hard.

My question is, is there a way I can prove this 100%. Or what can I do to rid the scale which is in the boiler's heat exchanger?

I have not tried the heating yet but will be soon, as is the scale problem going to affect the heating too? I do not know if my boiler has 2 heat exchnager or 1 so am not sure?

If the heating is going to be affected too, I'd like to resolve it soon obviously.

Any help would be very much appreciated.

 

[kevplumb]

1 get it descaled its a 4 pipe h/ex not a diy job

2 get a combimate fitted this is

View media item 15077

 

[stephendill]

Thanks for your reply

I have seen some scale redcuers, look like a tubr that you fit (push fit or compression fit) in line on the cold supply to the boiler.

I see, so is there no way I could add a de-scaler to the system myself then to try and cure it?

Is this scale likely to affect my heating circuit too?

 

[kevplumb]

Is this scale likely to affect my heating circuit too?

limescale wont affect your heating

adding anything to the system won't make any difference

dunno it this will make it clearer

View media item 15078

 

[stephendill]

thanks for helping me.

i am glad the heating side will not be affected, as you said i only have 1 heat exchanger then i thought it being scaled would affect both h/w and heating.

i see boiler de-scalers/silencers (for scaled up heat exchangers) in shops, are these no good then?

 

[kevplumb]

no thats for the heating side

there are 2 sets of 2 pipes running through your heat ex 2 are heating other 2 are hw

they don't mix

now i'm gonna hang a squirrel

ain't many monkeys in Tennessee

 

[stephendill]

Thanks for your help, So basically the inside of my cold pipe (h/w outlet pipe) in the heat exchanger is scaled up I don't know why though as the temperature is not over 60

There's anbsolutely nothing i can do....??

 

[kevplumb]

you can hire a pump and have a go yourself

but tbf is it worth the hassle

 

[kevplumb]

I don't know why though as the temperature is not over 60 icon_sad.gif

it is inside the boiler

 

[stephendill]

it shouldn't though as the temp was set at 60 on the stat is it because the scale over time has added up little by little due to the fresh water going in.

 

[kevplumb]

probably

 

[stephendill]

ah i see, it's probably a common occurence with combis then in hard water areas (most of england then)!

what pump would i need to hire to try?....

 

[kevplumb]

descaling pump

switch boiler off

then you need to disconnect the cold feed and the hot water outlet on the boiler connect the pump add a descaling chemical and switch pump on and wait

then reverse the procedure

 

[stephendill]

how much is this pump likely to cost!!!!!!





also is the cause of the water running cold all of a sudden due to the stat temp being reached / and then allowing only cold through until the temp drops again? i am curious to know why it is doing it???!!

 

[kevplumb]

how much is this pump likely to cost!!!!!!!

err anythin tween $1000 and $80000

also is the cause of the water running cold all of a sudden due to the stat temp being reached / and then allowing only cold through until the temp drops again? i am curious to know why it is doing it???!!

the water is running cold cos the boiler is shutting down the burner as the primary flow temp has bee reached

because it can't lose the heat to the hot water ie the secondary