Combi Boiler

[gazzae]

Hi All,

I have a combi boiler. I have the hot water set to 57oC. When I run a tap in the bathroom or kitchen sink the hot water reaches 57oC (The temp is shown on the front of the boiler). But when I run a bath the temp varies between 42 and 47oC. Anyone know what the problem might be? The central heating seems to be functioning fine.

[homealone]

check the respective flow rates of water from the sink & the bath - any significant increase in the bath taps flow rate will impact on the temperature the boiler will be able to heat the water to. If it does turn out that is the case, you could try running the bath tap a bit slower & see if that improves the temperature?

[banjo]

I would have thought it would have to do with flow rate, your bath taps are a larger bore and therefore larger flow rate and your boiler will struggle to fully heat this amount of water, try not opening the bath tap fully and I would think that the temperature will rise.

The down side is it will take longer to fill your bath

Note to self learn to type faster !

[gazzae]

The thing is though it seems to only have happened recently. I noticed it recently because the baths have gone from being hot to merely warm.

I don't think the flow rate has changed, still far slower than when we had an immersion heater.

[Taf]

We have just had this exact same thing... after the gas engineer changed the gas valve... one week later and no sign of him returning to sort it (something to do with the "low pressure setting").

The water flow valve should restrict the flow of water to maintain the temperature.....

[Xaccers]

Could the boiler need descaling of the heat exchanger?

[The Jackal]

boy do I hate combi boilers the plumbers love it cos its an easy system to fit.

Glad I took my missus advice and installed a boiler / megaflow pressurized cylinder system absolutely awesome since it gives you mains pressure hot water at every point in the house - no more hot an cold in the shower just pure power ahhh bliss.

[gazzae]

Originally Posted by Xaccers

Could the boiler need descaling of the heat exchanger?

How often should that be done, its only about 18 months old

[Xaccers]

Originally Posted by gazzae

How often should that be done, its only about 18 months old

Looking around on google, depends mainly on how hard the water in your area is, but many say between 1 and 3 years.

A guy I used to work with had his done and on their usual settings, the radiators went from being hot to being scalding!

[SMHarman]

Originally Posted by gazzae

The thing is though it seems to only have happened recently. I noticed it recently because the baths have gone from being hot to merely warm.

I don't think the flow rate has changed, still far slower than when we had an immersion heater.

Has the cold weather made the incoming cold water colder, a combi boiler specification is about temperature raise, so colder incoming water is still getting heated up be say 30 degrees, but it is 30 degrees from a lower starting point.

[banjo]

When I fitted my combi boiler I fitted a magnetic scale reducer in the cold water feed my boiler is now about 17 years old and is showing no signs of scale problems.

You can retro fit these devices and they can remove scale, just a thought !

Have a look at this and search for water descaler item number 316544

[Alien]

Originally Posted by banjo

When I fitted my combi boiler I fitted a magnetic scale reducer in the cold water feed my boiler is now about 17 years old and is showing no signs of scale problems.

You can retro fit these devices and they can remove scale, just a thought !

Have a look at this and search for water descaler item number 316544

Hmm... £80 is a lot of money for a technology that has been treated with some sceptism on the net in the past. I know, I know - anyone can say anything on the net, but it does make me wonder if these things are as effective as it's claimed they are, why aren't they for sale everywhere?

[banjo]

Originally Posted by Alien

Hmm... £80 is a lot of money for a technology that has been treated with some sceptism on the net in the past. I know, I know - anyone can say anything on the net, but it does make me wonder if these things are as effective as it's claimed they are, why aren't they for sale everywhere?

Well I can only go on my experience and it does seem to work, my shower head was always clogging up but now I can't remember the last time I had to clean it Oh and you can buy them at your local plumbers, they even do one that you just clip around the rising water main and is a permanent magnet that needs no plumbing skills as you do not have to break into the pipe.

---------- Post added at 09:21 ---------- Previous post was at 08:40 ----------

Try this site, can't get any more "main stream" than that product: 052010001

[j52c]

I had a similar problem to this last year, not saying it is the same as yours, but my water temp was lower upstairs.

My problem was that the diaphram in the switch over valve from central heating to hot domestic water had perished a little and so there was a hole in it.

I had a new one fitted and it solved the problem.

My Combi is 6 years old.

[Alien]

Originally Posted by banjo

Well I can only go on my experience and it does seem to work, my shower head was always clogging up but now I can't remember the last time I had to clean it Oh and you can buy them at your local plumbers, they even do one that you just clip around the rising water main and is a permanent magnet that needs no plumbing skills as you do not have to break into the pipe.

Cool.

Originally Posted by banjo

Try this site, can't get any more "main stream" than that product: 052010001

Thanks for that. I've bought a few things from them previously, plus it's cheaper than the other 1. Definitely something I might consider doing. The only prob for me is that being in a flat, my water pipe comes in through the bathroom floor. Fitting the gizmo wouldn't be a prob, getting power to it though may be more of a challenge.

BTW, direct link to the product's page, for anyone else who's curious, is here.