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Russ
14-12-2005, 13:14
I've got a combi-boiler.

Anyone have any idea why, if I keep the hot water on for about an hour, the water coming out of the hot tap when I run a bath is little more than a trickle?

Other times when I keep it on for an hour or so (or even longer), the hot water comes out at a good rate but is little more than lukewarm.

It's really annoying and sometimes running a bath takes ages.

homealone
14-12-2005, 13:44
I'm confused, Russ, what do you mean about 'keeping the water on for an hour'? - our combi boiler heats the water as you use it - keeping it on for an hour would overflow the bath??

Xaccers
14-12-2005, 13:51
Russ, does your combi have a hot water storage tank as well? (ours does, but my old one didn't)

etccarmageddon
14-12-2005, 14:15
some combis within the combi boiler itself have a small tank inside - these are the good ones which is to ensure the water is at a stable temperature.

not sure what you mean by having it on for an hour Russ?

perhaps your heating is competing for the boiler - try it with the heating turned off and see if that makes a difference.

jellybaby
14-12-2005, 14:37
Also ensure that the pressure on the boiler hasn't dropped. Mine sometimes drops and this affects the water temperature (goes up and down). I think it should be about 1.5 bar, but not more than 2

---------- Post added at 13:37 ---------- Previous post was at 13:30 ----------

just found this

Combination boilers have a pressure gauge which shows the water pressure in the system. The pressure in the system when cold is typically around 1 bar but your Installer should tell you the expected figure. The pressure will obviously rise when the system is hot but should not rise too much or anywhere near 3 bar pressure.

from http://www.gas-news.co.uk/consumerscombiuser.htm (here)

etccarmageddon
14-12-2005, 14:44
that's right - check the pressure guage. you should have a small tap near it which you can open up to repressure the system - you open the tap and let pressure rise until it gets to around 1 bar.

Graham M
14-12-2005, 14:52
I always thought that the pressure was for the heating system? :confused:

Wicked_and_Crazy
14-12-2005, 14:54
It's really annoying and sometimes running a bath takes ages.

You should only use enough to cover your vegetables ;)

ellie
14-12-2005, 14:57
You should only use enough to cover your vegetables ;)

Probably wont need much then :D

Russ
14-12-2005, 16:13
I'm confused, Russ, what do you mean about 'keeping the water on for an hour'? - our combi boiler heats the water as you use it - keeping it on for an hour would overflow the bath??

Sorry - it's not a combi :dunce:

I have to set my boiler for the water to heat up for about half an hour before it's warm/hot enough for a bath.

Sometimes when it's hot enough, it only comes out as a trickle, other times no matter how long it's been on for, it comes out a bit faster but is only slightly warm.

goldoni
14-12-2005, 16:21
Most combi boilers can deal with 9.5lt per min, but the other thing is temperature rise, which is normally about 49 deg.

With these two facts we have one more, the flow of the tap ie your kitchen tap will normally give a lower flow rate than your bath tap which is geared for about 15lt per min so if you slow it down so it is in spec ie 9.lt per min you should get nice hot water at about 60 deg, but it could take some time.

The combi boilers that have a storage tank is good for hand washing but not for running a bath.

The pressure dial normally should be at about 1.5bar but this will not effect the flow of the hot water, it could just lock the boiler if the pressure drops to 0,,,this would happen if you say bleed the radiators.

One problem with combi boilers is the gas flow, if you don’t put it in you can’t get it out so the gas feed pipe should be 22mm with the last part in 15mm. If you gas pipe is run mostly in 15mm this will need to be corrected.

Hope this helps

Well scrap that then,,,


Check the tanks in your loft, do you have any or do you have a sealed system

Halcyon
14-12-2005, 16:23
I have this problem too. And if I want a really hot bath I have to leave it for ages to fill up as it will be a trickle and not a normal flow.
Not sure what on earccauses this, but it can be annoying.
May be its because I no longer have a tank in the bathroom and it has to be pumped up stairs, I dont know.

Graham M
14-12-2005, 16:24
Hope this helps

Hehe it doesn't, read Russ' post just before yours :)

goldoni
14-12-2005, 16:37
Hope this helps

Hehe it doesn't, read Russ' post just before yours :)

Did see it after I posted :D but with this info Russ has two problems,,,,,

Nugget
14-12-2005, 16:39
Did see it after I posted :D but with this info Russ has two problems,,,,,

Trust me - Russ has got far more than 2 problems ;) :D

etccarmageddon
14-12-2005, 16:42
I always thought that the pressure was for the heating system? :confused:no hot water as well as I know from bitter experience when moving into my house and finding the dishonest people I purchased it from left it with a faulty pressure cyclinder - so I'd be in the shower and it'd suddenly run cold thus having to leg it downstairs and repressure the system to get the hot water backup.

---------- Post added at 15:42 ---------- Previous post was at 15:41 ----------

Sorry - it's not a combi :dunce:

I have to set my boiler for the water to heat up for about half an hour before it's warm/hot enough for a bath.

Sometimes when it's hot enough, it only comes out as a trickle, other times no matter how long it's been on for, it comes out a bit faster but is only slightly warm.sounds like you have a faulty thermostat in your heating system but I'm no expert so dont take that as a fact.

goldoni
14-12-2005, 16:43
Did see it after I posted :D but with this info Russ has two problems,,,,,

Trust me - Russ has got far more than 2 problems ;) :D

With his hot water silly ;)

etccarmageddon
14-12-2005, 16:47
I have this problem too. And if I want a really hot bath I have to leave it for ages to fill up as it will be a trickle and not a normal flow.
Not sure what on earccauses this, but it can be annoying.
May be its because I no longer have a tank in the bathroom and it has to be pumped up stairs, I dont know.if you're on a combi it's because of the nature of how combi systems work - high pressure but low flow rate. high pressure because it's pumped from the cold water mains. low flow because it's heated as it's pumped.

---------- Post added at 15:47 ---------- Previous post was at 15:45 ----------

Russ, if your heating isn't on then your boiler should be able to heat up a full tank of hot water within 15 mins. Also check your boiler - does it have a general temperature control on it - a knob you can turn say from 1 to 6 - if this is low then your water will not heat up quickly and also your radiators will only be luke warm.

Tightscot
14-12-2005, 17:10
if you don't have a combi then you probably have a hot water tank/cylinder - Usually in the airing cupboard covered in lagging. There should be a thermostat on the outside of this cylinder, stick it between 50 and 60 degrees for nice hot water. Also your tank/cylinder may be too small or clogged up with scale, particularly if you live in a hard water area. I recently fitted a new hot water cylinder, with built in lagging and a super fast recovery coil system. If i use all the hot water, i have a full hot tank in a matter minutes, whereas before it would take an hour or more to refill and reheat. The old cylinder had a good few inches of scale and sludge in the bottom of it! cost about £150 ish.

Things like washing machines and dishwashers will also draw hot water, reducing the amount of hot water available for baths etc. check if these are on when the problem occurs.

SMHarman
15-12-2005, 00:57
What he said ^ - do you have a hot water tank somewhere?

Russ
15-12-2005, 00:58
Yes, it's under my stairs.

SMHarman
15-12-2005, 01:01
How old is it? You're in Wales (last I heard! - is that soft water?)

Does your boiler burn with a nice blue flame.

Do you rent or own, if you rent, you should get an anual gas inspection anyway.

Russ
15-12-2005, 01:05
No idea how old it is, and yes the flame is blue.

I'm renting but I'm hoping to not be here long enough to care much more...

SMHarman
15-12-2005, 03:18
I would imagine that your tank is full of limescale, also have you checked that the header tank in the loft is filling properly, that could cause the loss of pressure.

Angua
15-12-2005, 09:09
Sounds like the old sort of boiler (not condensing) and we used to have a terrible problem with loss of pressure which dropped so often I had to get the "lock out" bypassed (a combi boiler) check your pressure and make sure you have no drippy hot taps as this will drop the pressure.

If you have a water tank (like an immersion heater) you have the other sort of boiler, in which case I would suggest you keep the water heating on for longer rather than just putting it on to heat the water when you want a bath. That way there is always hot water ready. But don't have the hot taps running long enough to empty the tank (they take ages to fill up again).

If you like a hot bath try turning the water thermostat up so you have to use less hot and add more cold.

bopdude
15-12-2005, 09:46
Yes, it's under my stairs.

Under your stairs ???? Is it a gravity fed hot water and pumped c/ heating or fully pumped system do you know ?? can you hear the pump kick in when you run the hot tap ( without c/ heating on ) , if the first then I would say that was half the problem, I don't think I have ever seen a hot water tank down stairs before :confused:

SMHarman
15-12-2005, 10:32
Does not matter where the hot water tank is as long as the header tank to feed it is above it.

Like heating, it is better to leave the water on continuously than cool heat cycle it, less energy is required to do this.

bopdude
15-12-2005, 10:46
Does not matter where the hot water tank is as long as the header tank to feed it is above it.


But surely if the tank is downstairs as opposed to upstairs on a gravity fed hot water system, the hot water has to 'work' harder to reach its destination as the cold water displaces the hot ????

As usual, I wait to be shot down in flames....

Xaccers
15-12-2005, 10:54
It's the height between the header tank and the water outlet that gives the pressure, so downstairs taps should give slightly more pressure than upstairs ones.

SMHarman
15-12-2005, 11:26
But surely if the tank is downstairs as opposed to upstairs on a gravity fed hot water system, the hot water has to 'work' harder to reach its destination as the cold water displaces the hot ????

As usual, I wait to be shot down in flames....The magic of gravity makes this work just happen. The weight of the water in the loft pushes the rest around the system. That water is about 10 metres above ground level so gives 1 ATM / Bar of pressure. I suppose if your plumber made pipe spagetti like in that pipe / plumber game it may cause problems, but generally no.

Maggy
15-12-2005, 13:07
I would imagine that your tank is full of limescale, also have you checked that the header tank in the loft is filling properly, that could cause the loss of pressure.

If I've got my facts right Russ lives in a soft water area.This really shouldn't be a problem.

I guess that there are a fair number of 'experts' here Russ but frankly the only way you can be certain is to get a hot water systems expert to take a look...Don't you have such an 'aquaintance' among your contacts?For a few pints? ;)

Wicked_and_Crazy
15-12-2005, 13:12
If I've got my facts right Russ lives in a soft water area.This really shouldn't be a problem.



He has already said in another thread that his iron is full of lime

Maggy
15-12-2005, 13:19
If I've got my facts right Russ lives in a soft water area.This really shouldn't be a problem.


He has already said in another thread that his iron is full of lime
He did? He has an iron? ;)

So where is Russ's location?.I've always thought Wales was a soft water region.:confused:

Edit:According to this site(look at the map) Port Talbot is in a soft water region..but I suppose he could be in a pocket of hard water.:shrug:

http://www.dwi.gov.uk/consumer/faq/hardness.htm

Angua
15-12-2005, 15:05
He did? He has an iron? ;)

So where is Russ's location?.I've always thought Wales was a soft water region.:confused:

Edit:According to this site(look at the map) Port Talbot is in a soft water region..but I suppose he could be in a pocket of hard water.:shrug:

http://www.dwi.gov.uk/consumer/faq/hardness.htm
Either that or his water is piped from a hard water area. :shrug: :rudo:

Salu
15-12-2005, 17:56
I have a question too about water heaters.

I am planning to have a new bathroom fitted and I am wondering whether to replace the water heater or not.

I have a separate boiler for the central heating.

I have a instant hot water heater. Chaffoteax or something..?

The water comes out of the tap very slowly and takes an age to fill the bath.

The heater is >15 years old I have been advised.

It is covered by a contract and has been repaired many times.

If anyone elsewhere in the house turns the either hot or cold taps then the flow almost stops in the shower. This may be normal behaviour with instant water heaters though, I have been advised.

Even if noone does this the shower sometimes sprays cold water out for no apparent reason. If I take the shower head of the hook to wash toes etc....:)

You then have to increase the heat and decrease the heat to fix this... (this could be the shower???)

The water pressure was tested by the water board and found to be within normal limits at street level and in house measuring a small drop in pressure with in the house (lead pipes?)

The shower is a mixer shower btw.....

Will replacing the water heater give me A) better economy b) stop the hot water cut outs (accepting that someone turning a tap on would)

Would this be the right thing to do if I have a contract on it? Should I not carry on with the contract as the heater is always repaired on the grounds that most of it will be new by now!

Have instant water heaters come on so much in 15 years? I know condensor boilers have but are these available as separate water heaters?

Thanks

Tightscot
15-12-2005, 18:43
your best bet is to get a power shower. You can use the power shower as long as the cold water feed is NOT off the mains - ie it feeds from the cold water tank - usually in the loft.

Also if you have lead pipes then you need these changig as you'll go mad or die if drinking water from them.