They're just heat exchangers for DHW boiler systems. Loads on eBay:
http://www.ebay.co.uk/ulk/itm/221711894584
I am getting a 80l thermopot mash tun and a 70l boiler from brew builder. Well 70l or 100l not sure yet. Have you used brew builder a few times? Recommended?
Can you put up a link for the pump you are talking about?