Spluttering and spitting water from hot water tap

[sula1]

Dear all,

We have changed a calorifier tank about a month ago and since changing it, we get lots of spluttering and spitting and aerated water from the hot water taps.

We have fully bled the system three times so there is no residual air from filling.

The water system is always pressurised at 2 bar so no air can leak into the system. The cold taps don't show any spluttering and the hot water tank is fed by the same pump as the cold water system.
The spluttering ends when the water in the calorifier cools down.
The water temperature is around 55 degrees.

We have fully changed the water in our tank from a very mineral rich water to a softer water and the spluttering and spitting seem to have reduced somewhat, but the water is still very aerated.

We have checked electrical leak in the tank from the element, but none is present, so no electrolysis is happening within the tank.

Tank is a Quick calorifier mounted vertically with connections at the bottom. Same mounting as our previous tank.

We don't know what else to check and cannot understand the mechanism for which air seems to be getting into the hot water.

Anybody had faced similar issues?

Thanks in advance.

 

[pvb]

Was your previous calorifier the same make and model?

 

[GrahamM376]

If it's mounted vertically with connections at the bottom, are you sure all the air been removed from the top of the tank? Where is the element - top or bottom? Although you say water temp is 55 degrees, symptoms are similar to boiling.

 

[Tiller Girl]

Our tank been having spluttering for 3/4 years. Nothing solves the problem for me!!! I suspect the air can never be purged and once it heats up the expansion vessel can't cope. It's been handy to turn down the thermostat to avoid the hottest water when it spurts.

If anyone has a bright idea I would like it as well!

 

[vyv_cox]

It is impossible NOT to purge the air from a vertical calorifier. Cold water enters at the bottom and displaces all the air through the outlet nozzle at the top. I can only contribute the fact that the heater in my motorhome does just the same. It's a Truma boiler, heated either by gas or by an 'electric blanket' wrapped around it. It is mounted low in the van with no obvious opportunity for air to enter it. If left overnight with the electric heater turned on the hot water in the heads always splutters first time.

The only suggestion I can make to the OP is that there may be a small air leak on the suction side of the pump. Air would accumulate in the calorifier but has no opportunity to do so in the cold supply to the taps. This doesn't seem to be an option for my van because the water supply is not pressurised, it is controlled by microswitches operating a submerged pump in the tank.

 

[richardbrennan]

I had similar problems some time ago cured by changing the thermostat.

 

[GrahamM376]

It is impossible NOT to purge the air from a vertical calorifier. Cold water enters at the bottom and displaces all the air through the outlet nozzle at the top.

But is it a vertical one or a standard one mounted vertically? The Quick one here shows all connections at one end - http://www.sheridanmarine.com/product/quick-nautic-boiler-b3-20l-calorifiers

Edit - just had another look at the Quick and they do show it mounted vertically as well so presumably the outlet has a stand pipe which would vent the air.

 

[yoda]

From the description I would worry about the tank being in the orientation it is designed for. Also if the thermostat is not working then the water can boil and produce steam which may well cause the spluttering. Is the hot water mixed with cold at the tank by a thermostatic mixer before feeding the taps? Are you taking water out of the tank from the hot water connection?

yoda

 

[ex-Gladys]

Whilst I get nothing like the OP's problem, I have pretty much found the way for me to minimise spitting is to have the taps on when filling the tanks, particularly from empty...

 

[VicS]

But is it a vertical one or a standard one mounted vertically? The Quick one here shows all connections at one end - http://www.sheridanmarine.com/product/quick-nautic-boiler-b3-20l-calorifiers

From the description I would worry about the tank being in the orientation it is designed for. Also if the thermostat is not working then the water can boil and produce steam which may well cause the spluttering. Is the hot water mixed with cold at the tank by a thermostatic mixer before feeding the taps? Are you taking water out of the tank from the hot water connection?

yoda

IYYWF that some of the "Quick" calorifiers can be mounted mounted vertically or horizontally, or ( in some cases ) inclined . AFAICS they can all be mounted vertically. As the diagrams show the one in the Sheridan ad can be mounted vertically horizontally or inclined.
but
the Op does not say which type of "Quick" calorifier he has fitted. but from what he has said I'd guess a B3 or BX type.
Nor does he say if he has an optional thermostatic mixer fitted

He says the water temperature is around 55° but we don't know if that's the actual temperature of the water in the tank or if that the temp from a thermostatic mixer.
If that's merely the temp delivered by a mixer then overheating/ boiling due to a faulty immersion heater thermostat is a distinct possibility.

 

[vyv_cox]

There is no mechanism that I can understand for boiling water. Coolant from the engine is not going to reach boiling point without far more serious problems that will affect the running of the engine. Immersion heaters cut themselves out before this can happen.

The OP said he fitted a vertical calorifier. I took him at his word and assume he bought the correct unit.

 

[sula1]

Thanks for all the responses.

trying to round up all the queries.....

Not sure what the old calorifier was, but certainly not a Quick.
The orientation was as per installation instructions. The element is in the bottom of the tank.
It has no mixer at the tank, just basic (non thermostatic) mixer taps at the sink. The temperature was clearly measured with just hot.

I struggle to believe that we haven't purged all the air from filling, so I'm intrigued by Vyv's suggestion of a small leak in the suction that perhaps wouldn't show in the cold side.... will investigate....

Meanwhile, grateful for any other ideas

 

[VicS]

There is no mechanism that I can understand for boiling water. Coolant from the engine is not going to reach boiling point without far more serious problems that will affect the running of the engine. Immersion heaters cut themselves out before this can happen.

The OP said he fitted a vertical calorifier. I took him at his word and assume he bought the correct unit.

Provided the thermostat works correctly! ( one of mine I noticed was getting the water in the north wing a bit too hot when I put it on recently . On to do list to adjust down a bit)

 

[pvb]

Not sure what the old calorifier was, but certainly not a Quick.
The orientation was as per installation instructions. The element is in the bottom of the tank.
It has no mixer at the tank, just basic (non thermostatic) mixer taps at the sink. The temperature was clearly measured with just hot.

I struggle to believe that we haven't purged all the air from filling, so I'm intrigued by Vyv's suggestion of a small leak in the suction that perhaps wouldn't show in the cold side.... will investigate....

Meanwhile, grateful for any other ideas

The hot water outlet on calorifiers has a tube inside the body which goes up to the top surface of the tank, so that it draws out the hottest water. See this picture...

The Quick calorifiers are approved for horizontal or vertical mounting, so I'd assume that the hot water tube goes right along to the far end of the tank (ie the top when it's vertically mounted). Despite this, it's still feasible that you might not be able to remove all the air. It could be that the air will gradually get removed and that the spluttering will go away.

Most new calorifiers come with a thermostatic mixer valve these days, and I'd certainly recommend that you fit one. It will cut down on the useage of hot water, and allow you to have the hot water in the calorifier at a higher temperature. This will result in more heated water being available for washing. As an additional benefit, it will remove the risk of someone getting scalded.

 

[duncan99210]

We've had this problem at times. I've come to the conclusion that what's happening is that some shore side water supplies have got a lot of dissolved gasses in them: heat the water in the calorifier and the gas comes out of solution, leading to the symptoms described. Tap runs for a short time, blows out accumulated gasses and then you just get hot water. Otherwise I can come up with no rational explanation as the cold water system, which directly feeds the calorifier, never suffers from this apart from the odd occassion when I've run a tank dry.

 

[owen-cox]

Whilst I get nothing like the OP's problem, I have pretty much found the way for me to minimise spitting is to have the taps on when filling the tanks, particularly from empty...

I expect you mean with the pump switched off. This will just help the pump prime without having air forced through by the pump. I have known a few systems where this was the only way to prime the pump after completely running out of water.

 

[idomeneus5]

This is also happening to me, both hot and cold, but has only occured since adding a filter in the system between the tanks and the pump

 

[yoda]

This is also happening to me, both hot and cold, but has only occured since adding a filter in the system between the tanks and the pump

That sounds like air being sucked in by the pump and pushed into the calorifier. The filter seal perhaps?

Yoda

 

[Tiller Girl]

My supplier suggested that but I was unsuccessful in making attempts to reseal those joints - if they were at fault.

 

[MM5AHO]

I've seen this too. It was a small leak at suction side of the pump introducing air. But I suspect the expansion vessel makes it seem worse by building up the pressure slightly higher than the pump delivers. (therefore hot at initially higher pressure than cold)