Refrigerant piping length
Refrigerant piping length
(OP)
I am new to HVAC design and need help on the following issue:
I have specified a number of house hold Split Units for an office complex. The split units are relatively small, most of them providing 3.2 kW of cooling. I need to run the piping for 25 - 30m, as the only available space for the condensers are at that distance. On the data sheet, it states that the piping length should not exceed 20m.
My questions:
1) How much would the efficiency typically drop if I would exceed the max piping length by 5m
2) How much would the capacity of the unit drop if I would exceed the max piping length by 5m
3) I have over-sized ALL the units by about 20-30%. Would this "contingency" be enough to deal with the extra 5 - 10m of piping?
Thanks
I have specified a number of house hold Split Units for an office complex. The split units are relatively small, most of them providing 3.2 kW of cooling. I need to run the piping for 25 - 30m, as the only available space for the condensers are at that distance. On the data sheet, it states that the piping length should not exceed 20m.
My questions:
1) How much would the efficiency typically drop if I would exceed the max piping length by 5m
2) How much would the capacity of the unit drop if I would exceed the max piping length by 5m
3) I have over-sized ALL the units by about 20-30%. Would this "contingency" be enough to deal with the extra 5 - 10m of piping?
Thanks





RE: Refrigerant piping length
RE: Refrigerant piping length
Thanks!!!!
RE: Refrigerant piping length
2. Is it the equivalent length ? Have you accounted for the fittings ?
3. Apart from specifying the maximum length, the manufacturers also indicate the maximum vertical lift allowed.
4. Best way forward would be to get a back-up confirmation from the manufacturers on the maximum allowable length (vertical and total) along with the drop in capacities for the length specified.
5. Split units for office ? How big is it ? Where does fresh (outside) air come from ?
HVAC68
RE: Refrigerant piping length
1) The 25 - 30m is horizontal
2) Yes
3) There is no nett vertical lift
4) Thanks, I would consult the supplier on the capacity drop
5) Fresh air is provided by means of a fresh air supply duct. The offices are small, in the range of 20m^2, therefore the units are sized at 3.2 kW and 5 kW.
Some background: This is a small offices complex within the concourse area of a large station. The client has requested changes to a HVAC system that was designed previously. I was not part of the previous design team, so I am changing the design to client specification. They requested the use of split units wherever possible.
RE: Refrigerant piping length
Trust the fresh air supply is treated and not untreated. Untreated fresh air can cause condensation.
HVAC68
RE: Refrigerant piping length