webasto thermo top c water pump

[Jrtm]

ok I've got a thermo top c in my boat now due to space and areas to put stuff it's not the best layed out system but given it has to fit around a old engine room and everything including the hull is wood and it having 2 water tight bulkheads I have to run it in as it is.

 

due to the above the stock pump isn't very powerful it's been replaced once due to my own fault of running it dry.

 

the system is split into 3 rooms but runs off a 22mm loop. the goes from the pump & heater direct threw each room and back to the pump & heater, the pipes have to run under the floor in room 2&3 but due to the 2 bulkheads has to run up and over bulkheads into room 1. all consumers are on 15mm pipes and join to each side of the loop (1 pipe to cold side 1 pipe to hot side as the fitting guide shows)

 

room 1 is in the hold this just has a small water heating tank for hot water (I want to add a small tube radiator for drying towels and coats ect)

 

room 2 is the engine room this has the header tank in and the webasto

 

room 3 is the back cabin this has a small under floor rad (this can be bypassed or flow controlled threw the rad input and out put pipes)

 

now I wish to add a rad into room 1 (the hold) this is very easy to do as will sit right next to the 22mm loop pipes and only needs a 6inch 15mm pipe adding to join the rad to the loop.

 

my problem is the stock webasto pump is week if I shut off the room 3 rad it's more powerful but due to size of rad it consumes quite a bit of the pumps flow, can you fit a second pump to these webasto systems? or even run 2 of the stock small pumps?

[Jrtm]

forgot to add if adding a second pump where is the best place to put it? half way round system or on return pipe before or output pipe after stock pump