Require "By-pass Kit" for single pump to DHW????

[catnipsta]

I have just installed a single impeller pump (ST Monsoon 3 br) to boost the DHW to entire house (4 outlets).

Do I need one of these ByPass Kits...

By-Pass Kit
The Kit consists of two adaptors which push-fit to the outlet connectors of the Pump before fitting the Hoses. The adaptors are connected by a small bore flexible tube. If a twin-ended pump is then run with one supply closed off on the outlet side i.e. basin or bath taps, toilet cisterns, washing machines, dishwashers, etc. the By-Pass Kit will ensure that the closed end of the pump maintains a low flow of water to prevent overheating and subsequent seal damage (See Fig 1). The By-Pass Kit can be retrofitted to any existing installation.

from

http://www.techflow.co.uk/tech4.html

Does anybody know whether I need one of these kits ?

Many thanks in advance

 

[catnipsta]

OK...I think I have found out the answer....

I believe that this only required for twin impeller pumps supplying multiple taps.

 

[chrishutt]

You have found the answer.

The problem with twin ended pumps feeding taps as well as shower valves is that they are sometimes triggered to operate for hot (or cold) only demand, resulting in the other end of the pump pumping against a dead end, which is not good for the pump (not sure why). The by-pass hose allows a small flow through the other end of the pump to avoid this.

 

[catnipsta]

Does this not mean that all twin-ended pumps should have such a loop?

Since, regardless of the number of taps supplied, there will always be times when either just hot or cold supply is required - even when supplying one shower mixer valve.

Imagine taking a long cold shower on a hot summer's day. Would that not damage a twin impeller pump without the loop, since the HW has nowhere to flow?

 

[chrishutt]

Shower mixer valves always take in a mix of hot and cold, even on the hottest and coldest settings. A by-pass will only be required where other taps are also connected.

 

[ChrisR]

Yours is a single ended pump.

As you quoted:

If a twin-ended pump is then run with one supply closed off on the outlet side i.e. basin or bath taps, toilet cisterns, washing machines, dishwashers, etc. the By-Pass Kit will ensure that the closed end of the pump maintains a low flow of water to prevent overheating

So why would you think you need one?

 

[catnipsta]

I was initially worried about it..cos of the supply to several taps, however after further research into it, I realised that I am ok with the single pump.


thanks in any case.