(Not) Hot water.

[fuzzy]

Fuzzy Towers recently celebrated "Turn on the Central Heating Day". Since this occasion, I have occasionaly suffered instaces when the hot water has not been as hot as I was accustomed to (tank stat set at 55 degrees for good washing up). SWMBO thinks she may have knocked something in the airing cupboard. I looked and she was refering to the 'Mid Position Valve'. This has a slideing doofer on it with markings W M and H. The doofer is currently over the H mark. My guess is the contraption has something to do with what gets heated and how long for. Am I right and should the doofer be over something else? I guess the W and H marks are water and heating.

[mrcharly-YHT]

This is probably a motorised valve - usually controlled by your central heating controller.

The lever that sticks out of it allows you to manually override the motor. Knocking it shouldn't do anything, unless you've managed to force it into one of the override positions.

Normally the lever is free-ish to move back and forth. To lock it into position, you slide it to the position and push it up into a slot.

[fuzzy]

What should the default position be? W, H or M?

[clarion]

W = Woman

M = Man

H = Hermaphrodite

Happy to help

[Greenbank]

What should the default position be? W, H or M?

Yes.

[EDIT] Post in here explains what happens: DIYnot.com > Which is knackered: boiler or timer?

[fuzzy]

Head -> Wall 

[clarion]

I would have thought that the H setting (being, I guess, heating & water) is the one you do want.  I would have thought W would be water only, and M manual override.

But, IANAPlumber, and I am guessing wildly

[eck]

H - Hot
M - Medium
W - Wet.

Simples. 

[rafletcher]

You can check if it (the 3 position, or mid position valve) is working by getting SWMBO to turn the heating on and off via the thermostat of time clock. Same with the water at the time-clock. You should see the lever move. If it doesn't then the actuator is possibly broken (a  not uncommon fault).  

With a 3 position valve, when the water and heating are on, the flow of hot water from the radiator is split - some to the heating, some the the hot water coil. This may slow down the rate at which your hot water heats up, though ultimately if should still reach the set temperature. Maybe off-setting the stary up times would help, or even raising the boiler stat temperature.

We have a two channel time clock and two separate 2-way valves, rather than a mid (3) position.  That way we can (should we want) have heating without hot water - for instance if we're away - but then again the cost of heating hot water is minimal compared to the cost of heating central heating radiators.

[Cyclops]

Which position the valve is in depends on what your CH system is doing at the time:

W - Water, hot water only
M - Mixed, hot water and radiators
H - Heating, radiators only

The valve should change position automatically depending on what you've got your central heating set to do

[rogerzilla]

The actuators (a little motor) often fail but can be changed without any actual plumbing work.

[fuzzy]

Thanks folks.

All seems OK now. I think it was probably a case of No.1 son getting in the shower too soon after No.2 son getting out. The heating being on, the water will take a tad longer to heat.

[inc]

tank stat set at 55 degrees for good washing up

Domestic hot water tanks should be 60 deg minimum  for Legionella control.

[Little Jim]

Thanks folks.

All seems OK now. I think it was probably a case of No.1 son getting in the shower too soon after No.2 son getting out. The heating being on, the water will take a tad longer to heat.

I find this very hard to believe.  Firstly how do you get two boys to take a shower on the same day?  Both taking a shower in the same week without physical violence being threatened is unlikely in my experience; and secondly I just don't believe that two of then would use a whole tank of hot water.  No, never. 

[fuzzy]

Thanks folks.

All seems OK now. I think it was probably a case of No.1 son getting in the shower too soon after No.2 son getting out. The heating being on, the water will take a tad longer to heat.

I find this very hard to believe.  Firstly how do you get two boys to take a shower on the same day?  Both taking a shower in the same week without physical violence being threatened is unlikely in my experience; and secondly I just don't believe that two of then would use a whole tank of hot water.  No, never. 

SWMBO is very, how can I put it? Persuasive? The main problem is, onece they are in, they are right sods to get out again. Hot water running out generaly does the trick

[clarion]

I can believe it.  I have a nineteen year old who would stay in the shower from August to May unless prompted to get out.

[Little Jim]

SWMBO is very, how can I put it? Persuasive? The main problem is, onece they are in, they are right sods to get out again. Hot water running out generaly does the trick
[/quote]

I have seriously considered putting a valve on the hot water pipe coming out of the tank to persuade then to finish a shower in a reasonable time.