Volvo D2-55 fresh water hot water cylinder heat exchange problem

[bowring]

Volvo D2-55 fresh water hot water cylinder heat exchange problem

Can anyone shed light on why my remote hotwater cylinder is not heating from the fresh water side of the heat exchanger.

I understand that the coolant passes through a heat exchanger inside the isotherm hot water cylinder but its not working

Is there a pump that circulates the water that could be blocked

Whats the best way to test it

Thanks is advance

[Dsanduril]

Usually no extra pump (but depends on distance from engine to tank). Most often this is caused by an air lock in the secondary loop. There are vacuum tools that are made to remove these bubbles, but the easiest is to make sure there is only one high point in the tubing/piping and put either a manual valve or an automatic air release there and burp air out of the system while the engine is running.

Multiple ups and downs in the hose run make this harder to clear and more likely to occur. Could also be a lack of coolant in the system, especially if the auxiliary loop is new.

[DougR]

Most likely the problem is as described by Dsanduril. However there were problems such as you describe in the very first version of the D2-55a engine, where water flow in the heat exchanger tank needed to be rerouted in order to get a reasonable amount of hot water from a house hot water heater. There was a VP service bulletin pertaining to the modifications, and I think there are other threads here on CF that deal with this.