Ideal ISAR HE30 no hot water

[radio_engineer]

Hi,

I have Ideal ISAR HE 30 boiler and have now lost hot water. Things were getting worse over the last few weeks.

When tap turned on hot water comes out for 20 seconds then temperature reduces to only slightly warm.

I have searched forum here, so I have suspected diverter valve cartridge , have checked cartridge. Valve operates OK. I have tested this by turning ON DHW and observing temperature of the CH flow pipes , they remain cold. hot water pipe also remains cold other than short initial burst of hot water.

When DHW operated boiler runs normal routine, burner light comes on but DHW pipe remains warm to cold. Then after short period of time unusual stuff begins,,, some noise can be heard inside the boiler, like small plunger or similar, CH water pressure gauge oscillates and short burst of DHW warm water comes out of the hot water tap. By this time burner shuts down and water gets cold again. I have taken the cover and I can feel very hot pipes leading to sealed burner above. If I leave boiler for few minutes and then let DHW out come hot water for 20 seconds and all process starts again. I can also hear some unusual sound inside boiler almost like trapped air bursts.

If it is not Catridge or Valve head , some sugest plate exchanger, how can this be tested ?

There are no Fault codes at all.

On controls I have DHW set at maximum

thanks

 

[radio_engineer]

Any ideas ? thanks

 

[engineerman]

blocked phx

 

[radio_engineer]

blocked phx

Thanks engineerman,

Is there any test to do before I start taking this part out ? It is right at the back so not even sure how easy is to remove. just want to make sure it is the faulty component.

I have found some posts , who claim to have cleaned this component. Does anyone here have any experience in cleaning these or perhaps it is waste of time and new part only should be fitted

Are there any tips to look for when replacing this part, to ensure simple job and no leaks?

do I need any specialist tool ?

Thanks in advance

 

[radio_engineer]

any ideas ? thanks

 

[engineerman]

does the return pipe get hot?
22mm to the right
yes change phx

 

[radio_engineer]

Latest update

After hot water performance got so bad over on Saturday, got desperate so I have attempted to fix the problem.

I have followed advice and suspected Plate Heat Exchanger blockage.

Turned off power, isolate all valves, drained boiler , had to take out main PCB, diverter valve head, front electrical panel, etc . It takes long time to drain this boiler and particular problem is poor location of the isolating valves below boiler. Left 22mm flow pipe isolating gate is difficult to turn as it was stuck. It seemed that use of flat screwdriver will damage the brass gate head so i used small key, very tight. Same problem with return 22mm isolating valve. DO not use flat screwdriver.

Be very careful when taking out main PCB box, as wire harness is tight and as you pull out PCB board, wires connecting will pull and twist diverter valve head. I have found that removing connection at the bottom of the diverter valve head is first step and then you can pull out main pcb plate out. I have removed PCB box from boiler.

Then remove , from left side, diverter valve head. This creates space you will need later. Then I have removed S trap , or sump for condensate. This is full of water , and I have found some sand inside. I have managed to drop one screw ! somewhere not to be found again.

Next step was to remove plate exchanger. There are 2 torx srews holding it in place. Plate heat exchanger was full of dirt and sludge and scale confirming blockage. Take care as you remove , as much more water will come out.

As I had no spare exchanger I have attempted to clean plate heat exchanger.

For this I have used washing machine flushing / cleaning product, followed by descaling product and some Fernox . First I have dried exchanger on gas flame. then I have poured plenty washing machine cleaning powder inside the dirty exchanger. When dry , cleaning powder will get deep inside. Then you pour some boiling water inside and you get reaction with all foam and dirt pushed out. Repeat this few times.
Next step was to add liquid descaler. This did not produce massive gain but it seem to have removed some dirt. Then I have warmed p HEX on gas to get this boiling. Much better result.

Final step was to leave Fernox cleaner inside exchanger overnight .

After all this effort, which is considerable, I have removed great deal of sludge and part was clean. I have found evidence of dirt inside other components in the boiler.

Rubber seals for plate exchanger are in poor state and one is nearly perished. I could not find replacement on Sunday so had to put them back with some silicone grease .

Put it all back , before filing boiler decided to check pressure in pressure expansion tank. I have found no pressure that I can measure but no leak. I have pumped up pressure to 1 bar with car foot pump. This is where next problem started. As I have pumped up expansion tank air pressure I have pushed water back inside the boiler which must have pushed some dirt back in to exchanger I have just cleaned and refitted. I should have disconnected braided pipe from hydro block. Another lesson !

As I have refiled boiler, purged air turned boiler ON and it works !

I have restored DHW , great result but few other problems noticed.

1. I can hear noise , like gravel inside boiler only when in DHW mode. I guess this is stuff I pushed out from expansion tank.
2. I have large CH water pressure range between hot and cold CH . When hot pressure is near 2 bar when cold it is virtually 0. I suspect blockage in expansion tank.

I have added Fernox to system. Plan to flush this out in the next few days

Question : how long should Fernox cleaner be left inside system and what could go wrong if left longer ?


My conclusion is that cleaning blocked plate heat exchnager ISAR HE30 is hard work and it is much better to replace with new part as it will save plenty of time and messing out with chemicals. Also new rubber seals are necessary which you get with new part. New part is ~ £100 on ebay cheaper but not sure on quality.

Only if you are on tight budget and plenty of spare time ,,,

Ideal ISARHE30 is very poor boiler, very difficult to repair, it was so difficult to access air top up valve and connect pump . Sump elongated screw is just against heat exchanger so you cant turn it, if you pull PCB box it twists diverter valve head, it all seems to be put together with no great care,,,

 

[engineerman]

you can buy the washers for the phx for around a tenner
not sure what u mean regarding air top up valve
auto air vent?
have u bled all the rads?
have you unblocked the exp vess flexi pipe?

 

[radio_engineer]

you can buy the washers for the phx for around a tenner
not sure what u mean regarding air top up valve
auto air vent?
have u bled all the rads?
have you unblocked the exp vess flexi pipe?

Air top up valave - I mean this is valve used to pump up air inside the expansion vessel.

There is no air inside rads , checked this.

Auto air vent also seems OK , when I was filling boiler , auto air vent was letting air out then stopped as water level raised. There are no water leaks from auto air vent.

This leaves only expansion vessel braided pipe. I think it is not blocked as when I was pumping air to top up expansion vessel it seems to have pushed some dirty stuff inside plat heat exchanger. Pipe may have got blocked since as I filled the system perhaps.

One end of braided expansion vessel pipe is easy to disconect but other end is behind boiler, no access. How can i test if there is a blockage inside ?

 

[shambolic]

Can I just add not helpfully that you should not have done any of this unless you are a gas safe engineer!
Did you check the ionisation probes?(must be done on EVERY visit to an Isar) after doing this did you take an inlet dynamic pressure, a gas rate and a performance test?
If not your leaving yourself wide open if anything goes wrong.
Ps easiest way to check plate hex is to take flow and return temps when on hw.

 

[shambolic]

Ps its not difficult to repair if you know what you are doing.
Phone Ideal for a fixed price repair