T90 xr boiling water

sallytree

I have a t90xr it had became very noisy, the filter in the shower and a y strainer at the tank in the attic were both cleaned and the shower blead the noise returned to normal.
But then there was another problem
when the heaters in the shower are turned it boils the water in the shower, the temp of the water coming out the head/hose is ok though. when the shower is turned the after a few seconds the water stops boiling and a few seconds after that you can hear the high temp stat click.
when you turn the shower back on the water is stone cold for a fair while, then it starts to heat up and the water boils again.
Also when the shower is running you can hear the pump coming under pressure and then returning to normal every few seconds.

I am not sure where to go from here as I am not familiar with how this part of the shower works.
It seems to me that the elements are not being turned off when the water heats up causing it to boil.

Bruthal

sallytree wrote: »

I have a t90xr it had became very noisy, the filter in the shower and a y strainer at the tank in the attic were both cleaned and the shower blead the noise returned to normal.
But then there was another problem
when the heaters in the shower are turned it boils the water in the shower, the temp of the water coming out the head/hose is ok though. when the shower is turned the after a few seconds the water stops boiling and a few seconds after that you can hear the high temp stat click.
when you turn the shower back on the water is stone cold for a fair while, then it starts to heat up and the water boils again.
Also when the shower is running you can hear the pump coming under pressure and then returning to normal every few seconds.

I am not sure where to go from here as I am not familiar with how this part of the shower works.
It seems to me that the elements are not being turned off when the water heats up causing it to boil.

The water will only boil or sound like it is, if the flow through the shower is too slow. The actual heat output from elements is constant.

If it is approaching boiling, water from the shower head will be far too hot. When a shower is turned off after use, the water in the tank does stop flowing, and the elements go off, but often there is enough heat in the elements to heat the water enough to click the overheat stat. When the shower is then used again straight away, it will for a few seconds be very hot, then cold, then the stat resets, and it starts heating again.

I am not 100% clear on your description. You say when the heaters are turned on it boils. What do you mean? Are you turning on the shower and there is normal flow? Or are the heaters coming on without any water coming out?

sallytree

Bruthal wrote: »

The water will only boil or sound like it is, if the flow through the shower is too slow. The actual heat output from elements is constant.

If it is approaching boiling, water from the shower head will be far too hot. When a shower is turned off after use, the water in the tank does stop flowing, and the elements go off, but often there is enough heat in the elements to heat the water enough to click the overheat stat. When the shower is then used again straight away, it will for a few seconds be very hot, then cold, then the stat resets, and it starts heating again.

I am not 100% clear on your description. You say when the heaters are turned on it boils. What do you mean? Are you turning on the shower and there is normal flow? Or are the heaters coming on without any water coming out?

Thanks for your reply.
when the shower is turned on and running with a good flow of water out of the shower head you can hear the water in the heater boiling. I tried it with the shower head off and just the hose and it does the same thing.
when it is boiling you can hear the motor/pump slowing down for a second and going back to normal for a few seconds.

sallytree

the filter and strainer were fairly well blocked, could the flow valve be partialy blocked, causing the pump to struggle and the water to boil?

Bruthal

sallytree wrote: »

Thanks for your reply.
when the shower is turned on and running with a good flow of water out of the shower head you can hear the water in the heater boiling. I tried it with the shower head off and just the hose and it does the same thing.
when it is boiling you can hear the motor/pump slowing down for a second and going back to normal for a few seconds.

The shower cant have both a good flow rate, and also be boiling at the same time, once it is being fed by a cold water supply.

If it is boiling in the heater tank in the shower, it will be scalding coming out of the shower.

Bruthal

sallytree wrote: »

the filter and strainer were fairly well blocked, could the flow valve be partialy blocked, causing the pump to struggle and the water to boil?

Yes they would cause it to get far too hot. So there was not a normal flow rate.

The elements put out a fixed amount of heat. When you vary the temperature with the dial, you are simply slowing down the flow rate for hotter water, and increasing the flow for colder.

So if the filters are clogged, the slow rate is too low, and the water will be too hot. Limescale in the shower element heating tank can also cause this.

Clear the filters and that might help it alright.

sallytree

Bruthal wrote: »

Yes they would cause it to get far too hot. So there was not a normal flow rate.

The elements put out a fixed amount of heat. When you vary the temperature with the dial, you are simply slowing down the flow rate for hotter water, and increasing the flow for colder.

So if the filters are clogged, the slow rate is too low, and the water will be too hot. Limescale in the shower element heating tank can also cause this.

Clear the filters and that might help it alright.

Thanks again for your help
This is what i cant really understand, there isnt a bad flow from the shower but it is still boiling,(i know this shouldnt happen) the water is only scalding hot when you turn it up to 10 or if you turn off the shower and turn it back on again within a few seconds. (maybe it is that the xr flow rate should be better than the si I had in before?)

As I said in my first post the shower was noisy due lack of water and it was only after the filters were cleaned that the boiling was noticed, and the filter and strainer were rechecked.

The water has extremely high Iron content this is what is blocking the filters.
I am just thinking, you mention lime scale in the tank could cause boiling, could a build up of iron do the same thing. Air in the tank could but it has been bleed many times at both the bleed screw and with the head off the hose, the hose held right down running the shower in cold for a while then alternating it between hot and cold.
thanks again

Bruthal

sallytree wrote: »

Thanks again for your help
This is what i cant really understand, there isnt a bad flow from the shower but it is still boiling,(i know this shouldnt happen) the water is only scalding hot when you turn it up to 10 or if you turn off the shower and turn it back on again within a few seconds. (maybe it is that the xr flow rate should be better than the si I had in before?)

As I said in my first post the shower was noisy due lack of water and it was only after the filters were cleaned that the boiling was noticed, and the filter and strainer were rechecked.

The water has extremely high Iron content this is what is blocking the filters.
I am just thinking, you mention lime scale in the tank could cause boiling, could a build up of iron do the same thing. Air in the tank could but it has been bleed many times at both the bleed screw and with the head off the hose, the hose held right down running the shower in cold for a while then alternating it between hot and cold.
thanks again

What you seem to be saying is, that the water sounds like it is boiling, but is not scalding hot coming out of the hose.

Is that what you are saying? That is not possible. If you think you hear it boiling, but it is normal temperature coming out of the shower, then what you are hearing is not the sound of boiling.

sallytree

Well there is a noise coming from the top right of the shower like a kettle boiling, the same noise continues for a few seconds when the shower is turned off, and a few seconds later there is a click like the thermal overload switching.
So now I am completely lost

Bruthal

sallytree wrote: »

Well there is a noise coming from the top right of the shower like a kettle boiling, the same noise continues for a few seconds when the shower is turned off, and a few seconds later there is a click like the thermal overload switching.
So now I am completely lost

Yes that is the sound of the water heating after the shower is turned off alright, which is not unusual, since the water stops flowing and the power to the elements goes off when the shower is turned off, but the elements still have a fair bit of residual heat in them which transfers to the now non flowing water in the heating tank, and that is what you are hearing.

My shower does the exact same after it is switched off after use, including often hearing the overheat stat clicking.

Dtp79

sallytree wrote: »

Well there is a noise coming from the top right of the shower like a kettle boiling, the same noise continues for a few seconds when the shower is turned off, and a few seconds later there is a click like the thermal overload switching.
So now I am completely lost

9/10 times what your describing Is lime scale buildup in your shower element. I don't know if iron will do this. Is your water hard ?