hot water tank hot at top and cool at bottom?

[sarahbee]

I have just changed the pump on my boiler and after changing it i have noticed my water from my tank for a bath is not very hot at all and after feeling it, it is hot at the top and cool at the bottom, could there be a airlock in the tank ? if so how do i release it?
Any help is much appreciated.

 

[wilhelm]

....pump right way round?

do a search on bleeding pump.

 

[sarahbee]

Wilhelm, i was wondering that

 

[ChrisR]

Putting a pump in backwards would not make the top hot/bottom cold particularly. There could be an airlock in the coil inside the cylinder which would reduce the heating efficiency. Look on the pipework where the upper boiler pipe goes in, there is likely to be a bleed point on it.

 

[Slugbabydotcom]

hot at the top and cool at the bottom

This is normal due to 'stratification of water' > translated means hot water rises to the top and colder more dense water goes to the bottom.

Does sound like you have an antipodean pump [upside down j/k] or more likely air in the pipe leading to your flow connection on the cylinder. It may have a vent pipe that needs manually bleeding.
Make sure arrow stamped on pump leads to this boiler flow connection.

 

[ChrisR]

Still don't see much significance in the direction of the flow in the primary. As we know some manufacturers specify the "reverse" direction. Any HW cyl will stratify.

 

[Slugbabydotcom]

Its not to do with reverse flow through the coil in HW cyl
Its to do with reverse flow through the boiler

 

[ChrisR]

That doesn't make much difference either!
DO tell me how it makes the cylinder stratify more!!

Diverter valves can let by a bit backwards, but that wouldn'tr make much difference.

 

[Slugbabydotcom]

For the second time today I may have to concede that I am wrong about something here on DIYnot

Its to do with reverse flow through the boiler

I made that statement after thinking of instances with multipoints that I have come across where the flow was reversed and the outflow was cooler than if it was in the right way. The flow arrangement through the heat exchanger in a m/point is different to boilers. After thinking more about it I find myself unable to qualify that statement at this time and leave it as a point to be proved or disproved. However fitting the pump according to the manufacturers instructions will mean that the boiler will then be working as they intended and its time to look for other causes.

Adhering now to the topic question. The cylinder isnt getting hot enough probably due to one of the following.
The water coming from the boiler isnt hot enough to start with implying that there could be a fault or incorrect setting of a temperature control >boiler stat or cylinder stat.
The water is hot enough but isnt circulating through the cylinder due to an airlock or other blockage.

Close the by-pass if fitted and turn your pump speed up to max for a while to allow all the force from the pump to go towards pushing any airlock through your system.

Just out of interest what is the make and model of the boiler?

DO tell me how it makes the cylinder stratify more!!

Who suggested that unorthodox circulation would make a cylinder stratify more
After accepting the fact that stratification exists which I am sure we all do then the only remaining point is that there isnt enough hot water for a bath

 

[doitall]

Who suggested that unorthodox circulation would make a cylinder stratify more icon_question.gif

I did

With modern HE cylinders it wouldn't make much difference

 

[ChrisR]

You were wrong then doitall!
Orthodox circulation "in at the top" promotes stratification, tother way is a bit more efficient for heat transfer.

I find myself unable to qualify that statement at this time and leave it as a point to be proved or disproved.

Really Slug. "I was talking bo***ks" would be another way of putting it?

 

[Slugbabydotcom]

"I was talking bo***ks"

No, without the rhetoric what I was saying was that I may have been talking boll@cks and admit I probably was talking boll@cks
Only when I have conclusive proof will I be prepared to say that I was talking boll@cks.

 

[sarahbee]

The boiler is a Glowworm Spacesaver 45-60, i have turned the pump around water is a little bit hotter now but not like it is still cool at the bottom of tank. On my tank i have a bleed valve on the bottom of it at the side, have opened it up and only a trickle of water comes out.

 

[Newboy]

That's probably the drain point for the cylinder - the bleed point should be on the boiler flow/return pipework

 

[sarahbee]

Thanks newboy for that, now would the drain point be very close by to the water tank or is it a case of it could be anywhere along the system?