Boiling hot water in tank

spyderski

Hi, don't know if anyone on here can help me; The last week or so my shower has been BOILING hot (you couldn't stand under it), you have to let it run for maybe 10 mins to cool down. Last night when taking Xmas decorations out of the attic, I noticed the water tank in the attic was full of hot water!

Having inspected things a bit, it seems like the immersion is over filling and "pumping" hot water up into the attic. I presume this means there's no cold water to mix with the hot, leading to the problem with the shower.

Any ideas what the problem is?

sanbrafyffe

cant make out what you are saying,,,is your tank(hot water cylinder) heated by immersion only or is it by another heat source such as a stove or oil boiler

is your emmersion knackered ,

whats your shower in the bathroom,,is it a mixer shower,eg needs hot and cold supply or is it one of these electric showers that requires hot from the cylinder

tip;;;;;pics always help

spyderski

Yeah, sorry, its a bit hard to explain.

Water is heated by either electric immersion or the gas boiler. Both result normally in hot water in the copper tank. In this case the hot water seems to be leaving the tank and being pushed up into the attic where it is filling the plastic tank in the attic.

The shower is a mixer type (Grohe) - theres a pump for it beside the hot tank.

I dont mind getting a plumber out to fix it, but if its something simple that i could fix I'd rather save the money!
I also don't want some plumber coming out, spending 30 mins trying to figure out the problem and then charging me even though he can't fix it (this happened me before in another house)!

cikearney

spyderski wrote: »

Yeah, sorry, its a bit hard to explain.

Water is heated by either electric immersion or the gas boiler. Both result normally in hot water in the copper tank. In this case the hot water seems to be leaving the tank and being pushed up into the attic where it is filling the plastic tank in the attic.

The shower is a mixer type (Grohe) - theres a pump for it beside the hot tank.

I dont mind getting a plumber out to fix it, but if its something simple that i could fix I'd rather save the money!
I also don't want some plumber coming out, spending 30 mins trying to figure out the problem and then charging me even though he can't fix it (this happened me before in another house)!

I came across this a couple of times

Is there a lid on tour tank if so the pipe the hangs over and drops into the top of the tank is either submerged in the water, connect to the lid via a 350 fitting or it is sat into a hole drilled out of the lid with no gap around it.

This creates a heating circuit between your hot water expansion pipe and your cold water storage tank causing it to heat up

spyderski

Theres no lid on the attic tank - there is a pipe hanging over the tank but its about a foot above the top of the tank.

Theres a pipe which enters the plastic tank near the bottom. This is the pipe through which the hot water is coming. If you put your hand into the tank you can feel the hot water entering via the pipe. This pipe comes into the attic through the hot press - i checked last night and its connected to the pump.

It seems that the pipe which should deliver COLD water to the pump is actually carrying hot water - seems like the copper cylinder is overfilling with hot water and causing this - is that possible?

cikearney

What is the pump connected to, did you not realise that the appliance is not working correctly, can you upload a pic of the pump with it's connection to the pump and cylinder

spyderski

The pump has 2 inlets - Cold in, Hot in. It has 2 outlets - Cold out, hot out. After leaving the pump both outlet pipes run under the floorboards. The cold goes straight to the shower, the hot has a split somewhere as the hot water in the kitchen tap is also pumped. None of the other taps in the house are pumped.

The shower was working perfectly until a week ago - the problem seems to have occurred as the heating is on way more since the weather is colder. therefore it seems to me that when the copper tank fills with hot water from the gas boiler, there is no cut off - the boiler keeps heating water and its coming out of the tank as overflow?

I can upload a pic & diagram this evening once I get home.

If anyone can recommend someone to come have a look at this, I'd appreciate it - it's an awful waste of money heating water we don't need!

sanbrafyffe

we could do with a few pics and yes its possible for the cold pipe to get hot as the expansion will happen up the cold feed,,,still a bit confused,,,probably that i aint giving the thread much time,,,seems your over heating the cylinder by some source,,,you will need pics or a wee video etc

spyderski wrote: »

Theres no lid on the attic tank - there is a pipe hanging over the tank but its about a foot above the top of the tank.

Theres a pipe which enters the plastic tank near the bottom. This is the pipe through which the hot water is coming. If you put your hand into the tank you can feel the hot water entering via the pipe. This pipe comes into the attic through the hot press - i checked last night and its connected to the pump.

It seems that the pipe which should deliver COLD water to the pump is actually carrying hot water - seems like the copper cylinder is overfilling with hot water and causing this - is that possible?

K.Flyer

Do I read you correctly?
You are saying that the water in the attic tank is heating up when you use the central heating and at the same time water is flowing out through the overflow pipe?

jimf

is it possible you have a faulty mixer tap in the house somewhere kitchen/bathroom
hot water mixing with coldfeed and passing back to storage tank through cold feed delivery from tank

TPM

Cracked cylinder coil?

sanbrafyffe

thought of this myself,,,common problem too and especially if the tank is of old age

TPM wrote: »

Cracked cylinder coil?

jimf

then water in heating sys would need topping up constantly and water from cylinder should be discoloured

not too well up in the plumbing side of things so please let me know if this is wrong thinking

K.Flyer

jimf wrote: »

then water in heating sys would need topping up constantly and water from cylinder should be discoloured

If its a vented systen and the feed and expansion tank is positioned higher than the cold storage tank and the coil in the cylinder is leaking this might explain the problem he is having.
On a closed system there might be an auto filling valve fitted or a filling loop valve left open which would allow the system pressure to be maintained.
On a good heating system there should be no discolouration of the water.
The leak on the coil may be only very slight but worsens by expansion when the heat starts to go through it.

Dtp79

K.Flyer wrote: »

If its a vented systen and the feed and expansion tank is positioned higher than the cold storage tank and the coil in the cylinder is leaking this might explain the problem he is having.
On a closed system there might be an auto filling valve fitted or a filling loop valve left open which would allow the system pressure to be maintained.
On a good heating system there should be no discolouration of the water.
The leak on the coil may be only very slight but worsens by expansion when the heat starts to go through it.

I don't think the attic tank is over flowing. If it was overflowing them what your saying makes perfect sense k.flyer. Is the tank overflowing spyderski??

K.Flyer

spyderski wrote: »

... the problem seems to have occurred as the heating is on way more since the weather is colder. therefore it seems to me that when the copper tank fills with hot water from the gas boiler, there is no cut off - the boiler keeps heating water and its coming out of the tank as overflow?

A few posts back, hence my theory.

Dtp79

K.Flyer wrote: »

A few posts back, hence my theory.

My apologies k.flyer. I'd say your spot on.

Outkast_IRE

Im after reading through all the posts here, and just with a fresh set of eyes has the immersion thermostat been ruled out ? is there a chance the immersion is left on to keep the cylinder always hot and now the stat is gone and its bringing the water to boiling and its managing to creep back up the cold feed etc.

If the immersion is in an always on postion i wouldnt rule it out , especially as he says he runs the shower for a few minutes before it cools down a bit.

Dtp79

Outkast_IRE wrote: »

Im after reading through all the posts here, and just with a fresh set of eyes has the immersion thermostat been ruled out ? is there a chance the immersion is left on to keep the cylinder always hot and now the stat is gone and its bringing the water to boiling and its managing to creep back up the cold feed etc.

If the immersion is in an always on postion i wouldnt rule it out , especially as he says he runs the shower for a few minutes before it cools down a bit.

Possibly but unlikely. I think he said he felt hot water flowing in through cold feed. Maybe I'm wrong.

K.Flyer

I did think of that initially, but by the wording of the posts it appears to only happen when the heating is on.
You know yourself, you would need to be looking at it to give an accurate answer.

Outkast_IRE

Dtp79 wrote: »

Possibly but unlikely. I think he said he felt hot water flowing in through cold feed. Maybe I'm wrong.

I find it hard to trust amatuers following pipes and guessing what they are doing.
But in the sitaution i described the cold feed would heat up , to an amateur he might say the hot is flowing but reallly convection has just brought the hot water up that far.

Honestly dont rule it out, the only reason i bring it up is that i encountered this situation a few years ago..........
It doesnt look like the op has checked in for a while maybe we will never know.

Dtp79

Outkast_IRE wrote: »

I find it hard to trust amatuers following pipes and guessing what they are doing.
But in the sitaution i described the cold feed would heat up , to an amateur he might say the hot is flowing but reallly convection has just brought the hot water up that far.

Honestly dont rule it out, the only reason i bring it up is that i encountered this situation a few years ago..........
It doesnt look like the op has checked in for a while maybe we will never know.

Ye true I agree. I've actually seen it with solar. But would an immersion heat right down to base of cyclinder though?

K.Flyer

Outkast_IRE wrote: »

... It doesnt look like the op has checked in for a while maybe we will never know.

As has happend many a time

GreeBo

it seems clear (to me) that the hwc is overheating and, correctly, overflowing into the cold tank in the attic.
so the question is, is it the coil or the immersion?
ensure the immersion is off to rule it out first.
assuming it's not the immersion, are your rads hotter than normal? if so it would indicate a problem with the thermostat on your boiler.
finally, do you have a back boiler behind your fire?

Dtp79

GreeBo wrote: »

it seems clear (to me) that the hwc is overheating and, correctly, overflowing into the cold tank in the attic.
so the question is, is it the coil or the immersion?
ensure the immersion is off to rule it out first.
assuming it's not the immersion, are your rads hotter than normal? if so it would indicate a problem with the thermostat on your boiler.
finally, do you have a back boiler behind your fire?

True. Immersion on or off the tank would still overflow if there was a hole in the coil

Outkast_IRE

Dtp79 wrote: »

Ye true I agree. I've actually seen it with solar. But would an immersion heat right down to base of cyclinder though?

yes if the thermostat is non functioning . Plus we dont know the cylinder size or type, it would happen easier in a small cylinder than a big one.