McLannahan
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| posted on 13/12/10 at 08:54 PM |
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How does (or doesn't) my heating system work?
Guys and girls - In my quest to ask two silly questions in one night...
I have an oil fired CH system. The boiler does hot water and heating. Hot water is on for 5 hours a day - 2.5 in morning and 3 in evening but
there's never enough water. I had a crappy shower this morning (wife didn't...there was a wasp in there  ) and it was lacklustre. Now
there's nothing left.
We do have a HW tank in the airing cupboard and I believe a water heater. I always left this switched off at the fuse board but noticed it's now
on. There's a switch on the inside of the cupboard which I "think" may be the switch for it - not sure how that should be - off or
on?
Anyway - is it possible that our system isn't producing hot water? Could the electrical alternative be working or not letting the oil version
work?
I'm completely confused by this and thought that 5 hours of hot water should at least provide a few baths and showers?
Can someone explain how my system may work, and what the switches do and how should they be configured?
Thanks all
Michael
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nick205
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| posted on 13/12/10 at 09:11 PM |
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I'd imagine the OF system is meant to heat the water and the HW tank has an electric immersion heater for back-up or stand alone HW heating
(that's how my parents OF system is set-up). What sort of age/condition is the system, might need some attention or a service to get the water
properly up to temp. Also, what capacity is the HW tank some are deceptively puny with thick insulation.
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rayward
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| posted on 13/12/10 at 09:12 PM |
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sounds like you have a "y plan" system,
the electric immersion heater is a backup incase your boiler packs in, so should be turned off normally.
there should be a 3 way motorised valve somewhere, which either directs the hot water from the boiler to the radiators, or through a coil in the water
tank, or to both if both are selected at the same time,
there should be a stat attached to the side of your tank, which may need adjusting, but basically you will only get one tank of hot water at a time,
until the coil has had chance to warm up the tank again.
so even if the hot water is on for 5 hours, you will still only get one tank of water unless the tank is emptied and has chance to fill and warm up
again
hth
Ray
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jacko
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| posted on 13/12/10 at 09:23 PM |
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http://www.locostbuilders.co.uk/viewthread.php?tid=143800
This may help
And after reading my link the answer was the 3 way diverter valve that was the problem
Jacko
[Edited on 13/12/10 by jacko]
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McLannahan
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| posted on 13/12/10 at 09:51 PM |
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Thanks chaps - Very good point Ray about the tank capacity, I didn't even think of that!
I think the system is working ok - just maybe me being stupid or it's misconfigured.
The boiler was serviced just last week and the engineer took out some sort of valve/jet that he said we no longer required as we have a newer plastic
tank?? Not sure what he meant or what that means but the boiler now fires on first go - not 30th!
Ray - The "stat" - What am I adjusting? Time, Temp, capacity?
Thanks all - I'm a little wiser now!
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gazzarose
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| posted on 13/12/10 at 10:18 PM |
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It does sound a bit like the 3way valve is jammed. Does the heating work fine and get up to a good temperature. My gf parents had a similar problem
but the other way round, loads of piping hot water but no heating. The 3 way valve is a motorised valve that sings from Hotwater/HW &
Heating/Heating. So its possible it jammed to the heating side. The valve looks like a brass valve with 3 pipes going to it but with a white box on
top containing the motor. There should be a small black lever poking out the side to use as a manual override if its jamemd. Try having someone
turning the heating between hotwater only to heating only and see if the black lever moves. If not then its jammed and you may be able to work it back
and for manually to free it up. If it still doesn't work have a play with the lever to try and set it at the mid position so it will supply heat
to the hotwater cylinder and the radiators.
Hope this helps
Gareth
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rayward
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| posted on 13/12/10 at 10:25 PM |
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tank stat is basically the temp the water in the tank has to get too before the valve/boiler shuts off, ours is set to around 55 deg C, which means
you can run a sink full of water and put your hands in without having to add cold,
Ray
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McLannahan
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| posted on 13/12/10 at 10:45 PM |
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Ray - Ours is set at 60 so I'll drop it down a touch!
Gareth - My valve doesn't seem to want to move but I've not forced forced it. The HW is on "Advance" now and the three
inlets/outlets are piping hot - a good or bad sign?
House is warm enough - radiators get hot (too hot to touch to be honest) but we always have it on for a short period, worried about the cost! It was
serviced (boiler anyway) just a week ago but I wasn't in to ask the questions and it would be great to have a bit of knowledge before I get
someone in or ask his opinion.
Nick - Could be that simple.How could I tell the capacity? Nothing obvious on the tank?
Thanks guys
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SteveWalker
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| posted on 13/12/10 at 10:56 PM |
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quote:
Originally posted by McLannahan
Ray - Ours is set at 60 so I'll drop it down a touch!
I'd check first, as I think the minimum recommended temperature is 60°C to prevent nasty things like legionella colonising your hot water
system.
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franky
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| posted on 13/12/10 at 10:58 PM |
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slightly OT but I only have my water tank on for about 3 hours a day(oil heating too) and it always gives out red hot water. Have you got the on and
off times set to suit you?
Ie water on at 0600 or at 07:30, on again at 12:00 off at 13:00 then on again at 17:00 off at 18:00, if you have the heating on around the same time
it saves cash too as the water from the boiler is already hot.
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gazzarose
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| posted on 13/12/10 at 10:58 PM |
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The 3 pipes being hot does seem like a good sign.as long as its not just heat conducting from the valve rather than hot water.is the hot water hot
from the tap?if it is but then then cools down gradually then it could just be the capacity.have you got a bath?i haunt in my house and i've got
an electric shower so i've only got a small dumpy cylinder.about 3 foot or so him and about 2 foot across.a full size cylinder is about 4 foot
high and about 2 1/2 foot across.keep an fwd on the valve at different heating/hot water program times and see if its in different positions.
Gareth
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McLannahan
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| posted on 13/12/10 at 11:11 PM |
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Steve - I'll leave it be for now then! Thanks for that.
Franky - Not OT at all, just what I thought! I thought 5 hours should EASILY be enough. We have two or three 5 min showers a day. Washing machine and
dishwasher heat their own water. I have 2.5 hours in the morning ( 5 to 7.30) and 6 to 9 at night! Good call with the heating too - I thought that
water came straight from the boiler 
Gareth - Water does start hot, just not enough of it! The shower has a right fit when it can't pull hot and cold at the same time, makes an
awful noise, spins up and spins down, coughs and whines...
Tank is about 4 foot high and 2.5 foot as you describe. It's a tight fit in a standard door sized cupboard and def. not the smaller one you
describe.
I'll move the heating to the water times (or vice versa) and shorten the water times too - I'd like to aim for Franky's timings!
Thanks everyone
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Howlor
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| posted on 14/12/10 at 12:03 PM |
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Having only scan read the previous posts it may be in there somewhere. You may have an airlock in the feed to the hot water tank. Mine has a bleed
screw close to the tank just before it goes in to the tank element. May be worth cracking it slightly if you have one to see if any air comes out.
I have our OF hot water on for an hour in the morning and an hour at tea time and it generates a full tank for a household of 4 people.
Steve
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Howlor
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| posted on 14/12/10 at 12:05 PM |
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Just another thought, when the shower is cold have you tried running the taps to see if they still run hot? It may be a problem with the thermostatic
shower valve?
Steve
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McLannahan
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| posted on 14/12/10 at 12:25 PM |
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Steve - I do have a bleed valve, I'll try that when I get home. Encouraging you only need 2 hours for your OF system to get a full tank!
I think when the shower decides to have a fit there really is no hot water - it's luke warm at best after a long wait so at least the shower is
in agreement with the rest of the plumbing!
Edit to add - I do think from what people are saying my system does work. We do have hot water (nice and hot) and we do have heating, it's just
there's no capacity in the hot water side, despite having it on for 5 hours a day! - not sure if that helps or muddles the waters!
[Edited on 14/12/10 by McLannahan]
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McLannahan
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| posted on 14/12/10 at 09:52 PM |
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Thanks again for all the advice everyone.
I've checked the bleed screw this evening and there's no air in the system.
I've now modified the hot water cycle to just two hours a day - at the same time as the heating.
I'll now monitor it to see if I get less water - If I do then that's almost logical and I know I have to increase my cycle a little. If I
get the same water - then even though it's not enough I'll save three hours worth of oil!
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