Boiler - what did I do?

[ed]

That a bit of a short question with a long answer. There are so many factors to take into account and usually more than one right answer.

[AnthonyL]

Oh it's easy to see what is mains and what is header. Mains gushes out - header - just stop it with your hand. But I suspect something has also been switched off as there's one stop c*ck that is more than hand-tight.

I do have other things to do. It's one of those properties where everything looks very nice and lots of things don't quite work properly. So in truth wife likes it more than me which is all that matters init?

Yes I'd already got the manual thanks - it's the Neon flashing sensor No 10.

[AnthonyL]

The property is a bungalow - the kitchen is at the front, the boiler is at the rear in a utility room. I'd estimate about 25m including up and down again. The 'posh' bathroom is nearer the kitchen and under the cold water (I assume) unpressurised tank and contains the "low pressure" warning electric shower.

The utility room has a mains fed shower cubicle and being right next to the boiler it works well. Good pressure and hot.

An instant hot might suit for the kitchen.

We're in a smokeless zone. Something else I've got to get used to - no burning rubbish in the back garden.

[Capitol]

If you have good mains pressure flow. IIRC a mains pressure tank suffers from the same problems as a combi in terms of flow rate when the incoming flow rate is poor. It is very difficult IMO to beat a good hot water storage cylinder and a 3 bar pump if you want to fill a bath fast.

[AnthonyL]

A) Boiler fed mains pressure shower next to the boiler both in the utility room where I was also using the little self contained hand held cleaner. Shower went cold - boiler "Fault on hot water sensor" light flashing.

B) Alternative shower in the bathroom (not utility room) has not worked since we've got here. It is electric, below a tank in the ceiling and just reports "Low pressure". No water comes out at all.

My post was primarily about what happened with A) and my initial post made no mention of B) which came up as part of thread drift.

[AnthonyL]

Boiler and shower in question are mains fed. Water gushes very nicely out of tap on the main line. Boiler was Gas Safe inspected in July prior to purchase, Boiler Service, Fit New Flue, Fit New Case seal.

[AnthonyL]

Because the steam from the steamer quickly filled the utility room in which the boiler (and the shower my wife was trying to use) resided. It just seemed too big a coincidence that it was the first time I'd tried this steamer in the utility room.

I thought (erroneously it turns out) that maybe the steam vapour was drawn through the boiler. I though this because there are instructions to not block the boiler door so I assume there was an airflow in that direction.

I thought perhaps that steam had condensed on something within the boiler (eg whatever this Hot water sensor was) and this was re-inforced by turning on the central heating (it was timed to switch off at 10am and it was by now 11am) and letting it run for 10 mins or so, warming up the boiler, and then finding out that everything worked

- the warning light had stopped flashing - and my wife could continue with her shower. I was not prepared to continue testing by trying out the steamer again.

It all could be very coincidental but it is all a bit too coincidental for my liking. We've been here 5 weeks and the shower has never before failed to come out hot. I cannot however say whether or not the "Fault on Hot Water Sensor" light has ever come on before or not - just that it did at that time.

For the moment I am inclined to discount any draw on the 13 amp socket near to the boiler but until I can rule in whatever the fault was then I cannot totally rule anything out.

[AnthonyL]

I guess I can put the extension cable on the socket and eliminate the steam issue by running the steamer outside, just leaving the load on the circuitry. We want some electrical mods done so we'll have some checking carried out at the same time.

[NY]

Having lived in several houses that had a hot water header tank in the loft rather than the hot water system being fed from mains pressure. And the difference in pressure between hot and cold taps was a real nuisance - balancing the temperature in a mixer tap.

A mains-fed system, whether it's heated on demand or heated in a hot water cylinder, is a huge, colossal, vast improvement - to get hot and cold water that are guaranteed always to be at identical pressure and flow rate to each other, even if that pressure may vary slightly from day to day. I'd never got back to a header tank.

[John Rumm]

Because TNP has a quasi religious carrot up his arse about combis[1], and has decided that none of them are capable of providing a shower, and no quantity of contrary evidence or facts can fly in the face of his belief!

[1] He is the anti-dribble ;-)

[John Rumm]

There are two basic options: 1) a combi with enough power to run two showers at once, or 2) stored hot water of some kind.

1) Is possible with a boiler power of 35kW or more, and if you are content with each shower running at no more than say 7 lpm. Keep in mind though that with both showers going the boiler will be running "flat out", so there will be no slack in the system if there are other users of hot water at the time.

The rest comes down to detail of the particular circumstances.

[John Rumm]

Can we point you at the DIY FAQ and Wiki for some of the background information on heating systems, boiler types etc:

Here is a reasonable starting places:

[NY]

The heating only goes off for a few minutes while you have a shower. The radiators stay warm for far longer than the time that the boiler is off. Indeed out thermostat sometimes turns the boiler off for an hour or so when the house has got up to temperature, before turning it back on when the house has cooled a degree or so to reach the "turn on" temperature which is always a bit lower than then "turn off" temperature.

And the boiler is left on all year round so we have hot water for washing up as well as for baths/showers. We use the thermostat for it proper purpose: turning the heating on if the temperature drops below the threshold. In summer this happens far less often than in winter, but you can still have the odd cold spell. I've never understood the logic of "it's summer now so the central heating is going to be turned off completely until autumn".

And our boiler can supply a bath running full on, which a *much* higher flow rate than one or two showers, with their restricted flow rte because of the throttling effect of only having little holes in the shower head. I tested this just now. Our shower took a lot longer to fill the washing up bowl, even on cold when the flow rate is maximum (*), than it did to fill it even from the kitchen sink hot tape, never mind the bath hot tap.

If anything, it is our electric shower which is more restricted: because of the rating of the electricity cable to it, we can only have an 8 kW shower, and the water never really gets very hot with that - even at maximum it's only *just* starting to get unbearably hot. Apparently it would have been a been a big (and therefore expensive) job to extract the old cable from the trunking and install thicker-core cable to allow a more powerful shower. Ironically, the old shower got hotter even though its power rating was lower than the new one - but the old one developed a non-repairable fault.

(*) Electric showers adjust the temperature by reducing the flow rate to get hotter water.

[NY]

We've filled our bath to the overflow and never had a problem with the water running cold, bearing in mind that a comfortable bath is a mixture of hot and cold water. With the hot tap turned full on, the water still runs just as hot when the bath is half full of water (and it's time to turn the hot tap off and the cold tap on) as when the tap is first turned on (obviously once the cold water standing in the pipes has run through!).

The only heat-on-demand heater where the water ran cold if you turned the water on too far was a little wall-mounted gas "Ascot" heater in the house that I rented at university. I've never experienced it since.

Mind you, our boiler is a big bugger - about 4 ft x 3 ft x 3 ft, outside on the patio. Not sure what its power rating is, but it was specced by a reputable heating engineer to replace one of similar physical size and (as far as I know) similar power that eventually developed a leak in the main heat-exchanger tank after about 10 years' use: thank goodness we had an open fire to heat the house and a kettle to boil water for washing up until we could get a replacement boiler fitted (and the shower to keep ourselves sweet-smelling!).

[Vir Campestris]

We have a gravity fed tank, and a pump on the shower.

We've turned the pump off. We don't need it, and the result is a shower that nearly washes me down the drain, never mind the dirt... and it's one of those showers that you can't set the flow rate.

It helps that the shower is downstairs, so we have about 20ft of head.

Andy