Baxi Combi 80 Eco

[stingo]

Hot Water Problem. CH is fine but when i call for hot water the boiler fires up for approx 20 seconds then cuts out, then reignites and then cuts out again following this cycle until hot tap is turned off. I can get hot water but only at a trickle from the tap. If i increase the flow of the water then it goes cold.

Both diverter valve pins operate when water selected
PCB looks fine (No burn marks evident)
Fan runs at full speed.
Pump is whirling and gets hot.
Diverter valve gets hot.
Heat exchanger gets hot.
but cold water outlet pipe from boiler is COLD / LUKE WARM.

Please advise!!!!

 

[ChrisR]

Hot water heat exchanger (very) blocked.

 

[stingo]

Thanks for the quick response Chris. I'd thought as much but just wanted some clarification. Would you suggest trying to clean it or just replacing it?

Many thanks.

 

[sus]

The correct way is to power flush the heat exchanger. I have actually used professional drain acid un blocker (one shot) this is how i did it.

Removed plate heat exchanger and flush with water and remove as much debris as possible then empty of water.

Place heat exchanger in sink with cold tap running slowly to avoid staining in sink, any spills splash water straight away.

Use funnel to poor in acid very slowly and leave until bubbling stops. Rinse and shake repeat as needed make sure it is thoroughly flushed.

Be careful of splashes as they will burn and or stain. The heat exchanger gets very hot as acid is working i use a couple of pairs of latex surgeons gloves, make sure the room is well ventilated. Use only on stainless steel. This will remove scale and magnesite but it gets hot and the fumes will strip your lungs best way is to power flush i have never had to replace a heat exchanger.

 

[stingo]

Is this a common practice within the trade? if so i will try it.

Many thanks

 

[gazler]

Hot Water Problem. CH is fine but when i call for hot water the boiler fires up for approx 20 seconds then cuts out, then reignites and then cuts out again following this cycle until hot tap is turned off. I can get hot water but only at a trickle from the tap. If i increase the flow of the water then it goes cold.

Both diverter valve pins operate when water selected
PCB looks fine (No burn marks evident)
Fan runs at full speed.
Pump is whirling and gets hot.
Diverter valve gets hot.
Heat exchanger gets hot.
but cold water outlet pipe from boiler is COLD / LUKE WARM.

Please advise!!!!

hi I had the same problem with my hot water and it was the diaphram had a hole in after it was replaced the hot water was lovely

 

[gas4you]

Both diverter valve pins operate when water selected

hi I had the same problem with my hot water and it was the diaphram had a hole in after it was replaced the hot water was lovely

Obviously not the same fault

 

[Agile]

Is this a common practice within the trade? if so i will try it.

We do clean HEs most of the time although not exactly as described above. This means we can complete the repair in one visit.

However, it is not very common practice in the trade. Most firms replace it ( after all the customer is paying! ). They also charge for the time taken going to get the new part. That helps to keep the bill higher and the staff dont get messy or risk injury from acids!

The explanation they give is that you never know if you have made it completely clear of any dirt!

Tony