Powermax 155x - Heat Exchanger

[Onetap]

I will need to take the xchanger off for a while as i need to descale it.

Do you? The lime scale forms on the secondary (domestic hot water side) of the plate heat exchanger, so you could leave it connected to the primary (boiler) side and connect a descaling pump to the 22mm secondary connections (disconnect the cold water feed and the hot water outlet) .

You can get obstructions on the primary side, but that would indicate sludge and a corrosion problem with the radiators through lack of corrosion inhibitors. That should not happen. The problem is most commonly with the secondary side.

PS the 3-way TMV on those is unreliable so |I'd suggest you ensure that it is working before getting into major bypass surgery on the plumbing.

 

[lgoochy]

I will need to take the xchanger off for a while as i need to descale it.

Do you? The lime scale forms on the secondary (domestic hot water side) of the plate heat exchanger, so you could leave it connected to the primary (boiler) side and connect a descaling pump to the 22mm secondary connections (disconnect the cold water feed and the hot water outlet) .

You can get obstructions on the primary side, but that would indicate sludge and a corrosion problem with the radiators through lack of corrosion inhibitors. That should not happen. The problem is most commonly with the secondary side.

PS the 3-way TMV on those is unreliable so |I'd suggest you ensure that it is working before getting into major bypass surgery on the plumbing.

I have turning the 3 way valve to get more heat into the hot water. In your expert opinion would i be best to renew this and then see what the water temp is like before I perform heart surgery on the boiler ?

I would even be prepared to just renew the damn heat exchanger if I could get it off without flooding my house. Why oh why didnt them mount this damn thing on a timber frame so you could get something underneath it to catch the water.

 

[Onetap]

would i be best to renew this and then see what the water temp is like before I perform heart surgery on the boiler ?

Yes; you can feel the temperature of the hot pipe in and the mixed pipe out of the TMV. If there's hot going in and the outlet is still too cold AND the TMV can't be adjusted, then the heat exchanger is probably working and the TMV probably needs replacing. The TMVs do fail in that manner.

As noted above it may not be necessary to remove the PHX to descale the secondary side.

 

[petit_pablo]

The mixer on the powermax is much more likely to be the problem