Shower V wife, I know I am correct.

[ss]

OK, so in the morning possibly before the heating comes on (not that it matters) wife uses the shower, (combi boiler) she claims it is sometimes cold and takes ages to heat up. I advised her to have less flow to start with...nope still takes ages. A shower at any other time of the day she says is fine. Apparently if she turns the shower on at a lowish flow and brushes her teeth first the shower is still cold.

I am NOT getting up at 6.00am to prove her wrong as I think she is talking a load of bollocks. I have given up trying to explain how a combi works as in heating the water you use and its not stored in a tank which cools down overnight.

Now accepting pipes will be colder in the morning and the water has a distance to travel I see no way its anything like she is complaining about.

Is there any other possible explanation that makes sense. P.S. I have never had an issue with it although tend to shower 1-2 hours later.

[Tim+]

Yes, faulty diverted valve. I?m guessing you?re showering after the CH has come on, she?s maybe showering before.

It?s just one possibility. I wouldn?t discount her story until you?ve tried it yourself at 6 am.

Tim

[Roger Hayter]

Rapid response from a combi depends on heating a significant store of hot water in advance. When central heating is on this is not a problem, and water heating is also on and the hot water response immmediat.

Older models i have had heat the hot water store automatically when the water heating is on but the central heating off, and therefore fire up periodically through the night. This obviously creates some wasted heat as the heat store conducts/convects some heat ot the environment. So there are two ways this can be avoided, at the cost ot the very long period your wife has noticed before hot water becomes available, perhaps a matter of minutes. (Assuming as stated that the CH is off)

One way is to have the hot water disabled by timer at night or other periods as set by a standard timer. This means that when the timer is not set for hot water 'on' you cannnot get hot water at all, and as soon as the timer switches hot water on the boiler fires up in advance of any demand for hot water flow.

However. more modern boilers have a setting (called "ECO" on my WB boiler) which means that even when the hot water is enabled by the timer the heat store is only heated when hot water flow is demanded. This means that in the morning it will take just as long as if hot water had just come on with the timer, but later the heat store is likely to be a bit warm when hot water has been used recently.

I think the ECO setting defeats the whole object of having a combi, but opinions differ.

The solution to your problem is either a) set the timer to turn hot water on half an hour before you want to use it or b) turn off the ECO setting if it is on. (With the ECO setting there is not much point in ever having the timer turn the hot water off.)

[ss]

Thanks I will check the settings tomorrow.

[Max Demian]

What's it like when the central heating isn't on at all? Some combis have a 'preheat' function that heats the heat exchanger periodically, but I've never found it necessary.

[anonymousrapscallion]

A long pipe run in the loft and poor lagging/insulation could explain the w ater taking a while to heat up for the first shower of the day. Another pos sibility is a failing thermostatic cartridge in the shower valve- I had ver y similar symptoms to what you describe each time my cartridge began to fai l (3 times in the last six years before I gave up and replaced with a basic mixer).

Regards.

Ant.

[ss]

From memory during summer months it works ok when heating is off.

[ss]

I dont think it is a long pipe run but cant be sure, shower cartridge 18 months old.

[Brian Gaff]

No one way out is to start the ch earlier and see if that fixes it. Brian

[Andrew]

During the summer the temperature of the incoming mains water is much higher too.

[Tim Lamb]

Could the shower include a flow switch such that hot is not called if there is insufficient cold flowing?

We have a similar issue with an Aqualisa shower which refuses to run hot at low flow settings.

[Graham Harrison]

In a hard water area it can pay dividends to keep the shower head free of scale. When it gets clogged the flow is reduced and the safety valve in the boiler stops the water heating so you don't get scalded. Try turning on another tap, the extra flow may be enough to start the boiler. Then decscale.

[Chris Bartram]

My shower with a combi does take longer to heat up when the heating isn't on (because the heat exchanger is cold), but the difference is only maybe 15-20 seconds.

You'd be advised to try a higher flow, not lower, or run a hot tap for a while to put some heat into the primary heat exchanger.

[Vir Campestris]

Imagine how many brownie points you will earn if you stagger down there at 6 one morning just to check.

Imagine how many more you'll have if you prove her wrong...

You _do_ want to stay married?

Andy

[Roger Hayter]

Makes sense.

I'm not sure you understand how these things work.

In which case a solution would be good, proving the original observation was wrong would be less helpful.

[tabbypurr]

It did seem the wrong attitude for that

NT

[Fredxx]

suggests if the incoming water is cold, depending on pipes, heat exchangers and shower heads, below a certain temperature I am wondering if there simply isn't enough flow to fire the combi.

Where is the combi? Can she confirm it is lit after running the shower?

Perhaps turn on a hot tap too to get it to fire, and turn off when it has fired?? I do this as I want the shower tray to have warm, and not cold water!

[Fredxx]

I might have thought this would have the opposite problem? With the cartridge stuck in the cold position for a long time allowing 100% hot water through. It would have poor temperature control, something the OP can check.

[ss]

After 40+ years of marriage she still cannot comprehend things like thermostats (electric blanket must go on 2 hours before going to bed) and (ovens must be preheated for at least an hour)

So I will give her a checklist for the mornings when the shower is apparently cold. Like is the heating on or off, I reckon when she has a checklist I will never hear anymore about it. Hopefully :-)

[Chris J Dixon]

A good few years ago I had a protracted dialogue with site services because of problems with the aircon system - they were eventually convinced that having it all locked off with no user controls wasn't working. There seems to be little understanding that you need accurate control, but quite a large band between heating and cooling.

So, they gave us a small control panel, which showed us the state of the three heating stages. Even when all three LEDs were on, especially on a cold Monday morning, there were those who insisted on winding up the setting. This was in an office full of professional control gear engineers.

Chris