Ideal ISAR HE30 Problems

[mark.horsman]

Hi, I have a Isar HE30 combi boiler and a few things are begining to get on my nerves.....

1) During CH mode the boiler pump runs on for 4 minutes after the CH demand has gone. It's a good idea to equalise the water temp around the system, but not so good if your programmable thermostat turns the boiler on every 10 minutes to regulate the room temp. The flame only lights for 30 seconds - then it's 4 minutes of overun. Aaagh!

2) During the overun above if the system recieves a DHW demand - BANG, the changover valve switches mode whilst the pump is still running. Hydraulic nightmare!! Anyone else seen this problem?

3) Air, air and more air whilst in DHW mode. 4 months and the system is still boiling of air! or is it I don't know?

Can anyone cast any info on the above probelms/annoyances.

Mark

[John Rumm]

Given the pump ought to be almost silent, who cares?

No, the diverter will make a audible click when switching - but I would not describe it as a "bang". There is little difference in its activation sound from the boiler being in standby or CH mode IME at the time of the HW demand.

Air where exactly? Coming out the hot tap?

[Ed Sirett]

I think that you may have all or most of the radiator effectively off on the TRVs and so the boiler quickly heats up and then stops.

Check and review the setting of the TRVs and the Programmable T/stat.

[mark.horsman]

for relying.

My programmable stat is a Danfoss Randall TP5000. It actually turns the boiler on 6 times an hour when heat is required, some times for only 30 seconds to top up the temperature of the radiators.

[mark.horsman]

1) The pump ain't silent it rumbles. It's in the kitchen and it's annoying. 2)When the diverter valve switches over the water is at full flow too and from the boiler.... so it hits the back of the claosed valve and bangs - water hammer. The whole central heating system convulses so it's a bang audable throughout the house. The pump stops when the valve is changing from DHW to CH but obviously doesn't when changing from CH to DHW, Ideal aren't interested. 3) The air is in the boiler closed circuit - it clears when the system switches to CH as it can be heard entering the first rad. When DHW runs again the air slowly builds up... Again Ideal aren't interested.

Mark

[John Rumm]

In the same room as the boiler I can't hear the pump over the fan of the boiler. Could there be a fault with the pump?

I must admit to never having listened carefully to exact switchover sequence on my HE35 to know if it is doing the same as yours. However, I have never been aware of anything more than the polite "clunk" of the diverter valve and the speed up in the fan when switching from CH to HW.

Is it air or hydrogen? (i.e. does it burn if you try to ignight the gas as you bleed it from a rad).

If it is air, and you are sure that it is only/still getting into the system while in HW mode[1], then that would indicate the fault in the boiler I would have thought, since the primary heating loop is only running through the main and plate heat exchangers, the pump and the diversion valve.

If it is hydrogen, then that would indicate a fairly active corrosion problem. Is there sufficent corrosian inhibitor in the primary circuit?

Is it loosing water - how often do you need to top up the pressure?

[1] Could it be that air is getting in all the time, but you only become aware of it in HW mode because a slug of it is released in one hit, rather than being fed in over time?