There's no such thing as a daft question...

[darsuke]

...but it' a genuine query if you don' know the answer so;

In my traditional (non-combi) water/heating system, how does our hot water storage tank receive its hot water?

I'd like to assume the boiler heats water then feeds it into the storage tank. Don't think it does though judging by how much cold water leaves the hot taps.

If it's not doing it that way I assume cold water feeds into the storage tank.
So how does it then get heated up?

 

[HardwareGeek]

Google "hot water cylinder coil" for pics, the boiler has a hot water loop that is separate from the actual water you use and this is heated and pumped through a coil inside the hot water cylinder to transfer the heat into the cold water etc

 

[HardwareGeek]

also cold water from the hot tap will be water left in the pipes that has cooled and needs to come out the tap before the hot feeds through afterwards from the cylinder

 

[darsuke]

Google "hot water cylinder coil" for pics, the boiler has a hot water loop that is separate from the actual water you use and this is heated and pumped through a coil inside the hot water cylinder to transfer the heat into the cold water etc

Thanks, it's helpful!

So I think ours is an unvented type and presumably indirect thus the gas boiler is heating the water.

The reason for trying to understand is we can't even run a bath of hot water. The tap runs cold before the (big) bath has chance to fill. And we can't top it up because of the length of time it takes to get the tap water hot again.

Is changing system type to a combi style a very large operation?
Lots of underfloor pipework alterations for example?

 

[Adam_151]

You should be able to get enough hot water for a bath unless its the size of a swimming pool. If you think about the relative size of the cylinder and the bath and then consider that you'd need quite a bit of cold in as well as the water in the cylinder should be far too hot to bathe in. Then something sounds like it is wrong

 

[theone8181]

There is a thermostat on hot water tanks which i presume you must have.

 

[darsuke]

You should be able to get enough hot water for a bath unless its the size of a swimming pool. If you think about the relative size of the cylinder and the bath and then consider that you'd need quite a bit of cold in as well as the water in the cylinder should be far too hot to bathe in. Then something sounds like it is wrong

It's probably larger than average bath, nothing extravagant mind. But been the same the whole 6 years we'e been here. Not telling you how many baths we had in six years

Getting our own place shortly and that too isn't a combi style. We just been put off traditional systems so considering what works involved getting it changed to a combi.

 

[darsuke]

There is a thermostat on hot water tanks which i presume you must have.

Yes, it has one.

It is showing at about 65 (manual style) but held in place with a net curtain wire!

Not sure if it actually works or not.

 

[PlacidCasual]

The net curtain wire is standard, I have a tank stat only fitted a year ago and it's exactly the same. Tank stat is important otherwise your boiler just keeps heating the tank if the hot water is on irrespective of whether the water needs it.

 

[darsuke]

The net curtain wire is standard

Actually when @HardwareGeek had me googling I did see quite a few YouTube clips with curtain wires around the tank. Must be common then

 

[Psycho Sonny]

Thanks, it's helpful!

So I think ours is an unvented type and presumably indirect thus the gas boiler is heating the water.

The reason for trying to understand is we can't even run a bath of hot water. The tap runs cold before the (big) bath has chance to fill. And we can't top it up because of the length of time it takes to get the tap water hot again.

Is changing system type to a combi style a very large operation?
Lots of underfloor pipework alterations for example?

if your tap runs cold before it's had a chance to fill then either you aren't sticking your hot water on for long enough or it's not being heated up properly.

i heat my tank up for 1 hour 2 times per day. enough hot water in it to have a bath and a shower and do the dishes.

you say you have been put off traditional systems but traditional ones are far better IMO. for instance i have 2 gravity fed showers (not electrical) after using these i would never go back to electrical. it also means 2 people can have a shower at the same time without any temperature issues. try doing that with a combi.

the old traditional system is fine. there is something you are doing wrong or there is something wrong with your system. i have mine set to 55 degrees so if yours is 65 then something is definitely wrong. no way should it be running out.

 

[darsuke]

i heat my tank up for 1 hour 2 times per day. enough hot water in it to have a bath and a shower and do the dishes.

Ours is 50 mins two times a day for showers and dishes. Its fine for work days but we supplement it on days off.

We can run a bath if we plan in advance but no impromptu ones. The knack is to fire the boiler for 2 or 3 hours so the water gets really hot and run the bath tap slowly.

We assumed turning the bath tap on full would fill it quicker avoiding it running cold but the opposite is true.

 

[Psycho Sonny]

Ours is 50 mins two times a day for showers and dishes. Its fine for work days but we supplement it on days off.

We can run a bath if we plan in advance but no impromptu ones. The knack is to fire the boiler for 2 or 3 hours so the water gets really hot and run the bath tap slowly.

We assumed turning the bath tap on full would fill it quicker avoiding it running cold but the opposite is true.

running it for 2-3 hours won't get it any hotter than whatever it's been set at. so 65C. all your doing is keeping it topped up to 65C.

my tank is insulated got a jacket for it out of homebase for £5-15. it's also in a tight enclosed space so if heat does escape it doesn't travel far. i've been thinking of even insulating the inside of the door to the storage cupboard it's in to further increase efficiency.

running the bath tap slowly it should be losing energy quicker as room temp in the bath is below the temp of the water. it doesn't sound like you know much about how the whole system works. your tank has like 100L of hot water in it. it shouldn't be running out. especially as 65C would be scolding hot and need to be mixed with cold water to be able to be usable.

 

[darsuke]

running it for 2-3 hours won't get it any hotter than whatever it's been set at. so 65C.

Well it is what it is and hasn't changed in all the years we've been here. I guess the 50 minutes of burner time isn't enough for it to reach that 65 operating temp then. Longer periods do allow us to get a hotter tank but it's such an old style inefficient boiler it's not something we like doing regularly.

it doesn't sound like you know much about how the whole system works.

Haha well you're right, that's why I asked. I do now see what system I have currently and the alternative methods out there thanks to all that helped though

 

[Skullroses]

Hi, looking for help. We've got a condensing boiler and a hot water tank. Our boiler has been broken for 17 days so had no heating or hot water. Long story! However boiler is now fixed, heating is working fine however we've still no hot water. How long should it take before we the tank has hot water?!

 

[HardwareGeek]

Depends on how big the cylinder is and how many kw the boiler is and design on cylinder how much heat it can absorb, whether your boiler output is split between heating at the same time or just hot water etc

but as a general estimate assuming it is working correctly between 30 mins for the most amazing system to 1.5hrs i would say from a totally cold to fully hot cylinder.

but you should notice it warming up the pipes within 10 mins really if you touch the pipe coming from the top of the cylinder, and or feel the flow pipes going in/out of the cylinder to heat it

EDIT- you would hope they checked it was working properly before leaving, and didnt make any silly mistakes like leave the cylinder stat turned down etc

 

[DXP55]

When I had a hot water tank I used to leave it permanently switched on - I don't think it used any more oil than timing it - If it's hot it doesn't need a lot to top it up - leave it all day and it is on much longer.

I now have a combi and it is worst decision I ever made - should have had a pressured tank system - with basic condensing boiler - My WB oil boiler has cost me a lot of money in yearly services and odd break downs . My old Eurocal non condensing did 20 years service without a problem and was good on oil.