Low Loss Header

[Barney12]

I was doing some 'research surfing' and came back to a link I had saved previously.

 

This pre-plumbed board for ASHP's has a "Low Loss Header". My questions are thus:

 

1. What the heck is it?

2. Why is it needed?

 

 

[PeterW]

It's a baby buffer tank that allows primary and secondary separation of flows. 

 

Need them on some boilers to ensure flow rates are maintained but not sure why you need one on an ASHP if you have a bypass valve as the heat input of an ASHP is nowhere close to the input of a boiler. 

[Nickfromwales]

It sometimes helps to stop short cycling, ( pump turning on and off repeatedly if the produced heat and flow exceeds the current demand of the load ) eg like you blowing down a straw but your finger is covering the end. 

Another use is to combine the output of two ( or more ) like sized appliances, eg if you wanted 2 X 15kw ASHP's ( to combine their output to get say 28kw output ) then you'd connect both of them to a low loss header so they could both pump / circulate to the header, modulating accordingly if required, whilst free flowing. Then another pump would be used to draw off the header to service the load in accordance with demand. 

I priced a job a while back which would have needed 3 ASHP's which would have been connected to a LLH, but not requiring their combined max output. I over spec'd the job so it could run off 2 whilst the 3rd was down for maintenance / repair but all 3 would combine for low output, long life operation. Good option for failsafe where one huge heater would suffice, but multiples would be laboured less and offer redundancy. 

[Barney12]

I managed to find a YouTube video that suggested that the Samsung units are "fussy" about flow rates. It suggested that the LLH meant that a smaller pump could be used.

Does that make sense?

 

 

Edited March 28, 2017 by Barney12

[Nickfromwales]

The pump needs to be suited to the appliances max output ( sustained ) so sounds strange to me. . Most pumps can be set to their lowest setting on the side of the pump, whilst some are 'intelligent' and do this themselves, so quite bizarre TBH. 

[Jeremy Harris]

I suspect the Samsung may be like the re-badged Carrier unit we have, in that it has an "over-pressure" alarm and shut-down if the flow gets obstructed.  As @PeterW says, I'd have though the bypass valve would deal with this problem OK, it does on our installation.

Edited March 29, 2017 by JSHarris