UPS specification for pool pumps

[SJD]

Background
A pool installation uses two single phase pumps to circulate the water (through a boiler, and filtering, dosing etc). The pumps are controlled via contactors in the pump house, plus a remote emergency stop close to the pool. The location is somewhat rural, and prone to power cuts, usually of a short duration. If there is a power cut, the pumps can be tripped until someone notices - usually when the pool is planned to be used - e.g. the next day or after several days. By which time the water can be too cold or out of spec re dosing etc.

Question
I've been asked would it be possible to put the pumps on a UPS, so short duration power cuts don't trip them. I can see issues with the contactors and emergency stop if not properly thought out, but that aside, I'm wondering about the UPS rating. The type label for the pumps is attached, but I'm thinking the UPS would need a somewhat higher rating (than 2x what is on the label) to cope with starting currents, but UPS specs are a bit beyond my expertise (I haven't a clue).

I'd also be interested in any comments as to why it might not be a good idea (I don't especially want to do it)!

 

[James]

If you put, say a 3kw ups on the whole lot, pumps, control and boiler (maybe the pool DB entirely)
It will sort out short duration cut’s however if it is long enough for the battery to deplete, it is still likely to trip something.

 

[SparkySy]

I think I'd be looking more at 6kw to run the whole lot.
And depending on the length of the power outages I'd be suggesting a generator if they were lengthy.

 

[James]

Perhaps it would be a better solution to have some sort of alarm that alerts people to a fault or out of spec. Temperature?

 

[SJD]

Perhaps it would be a better solution to have some sort of alarm that alerts people to a fault or out of spec. Temperature?

This might help sometimes, but if there is a power fail late Friday, and nobody is around till after the weekend, that is 2 to 3 days when the pumps maybe could have been running but weren't. Unless the alarm was sent to a mobile phone I suppose, and someone could then visit (which in itself might be an issue).

 

[SJD]

I think I'd be looking more at 6kw to run the whole lot.
And depending on the length of the power outages I'd be suggesting a generator if they were lengthy.

If you put, say a 3kw ups on the whole lot, pumps, control and boiler (maybe the pool DB entirely)

It was suggested to me to put the Pool DB on the UPS, there is not much unrelated connected (just a few lights, I think).
Total would be no more than 3kW (when running).

But do I need to then uprate the UPS (e.g. to 6kW or more) to cope with pump start-up currents? Or do typical (decent quality) UPS cope with start-up surges?

 

[Avo Mk8]

I hesitate to suggest this, but Is it too risky an idea to consider automatic restart of the pumps after power is restored?
I've heard of an implementation putting the nc contacts of a short delay period timer (eg a second or two depending on how cleanly power usually comes back) across the 'start' button for each pumps contactor.
This could be a stupid risky idea, or if it's electrically sound, it could be a cost-effective mod that the owner could 'switch in' when needed?
I would have thought the boiler would restart by itself, maybe once it sees flow, but is there other equipment that packs up as well, meaning you really do need UPS power?

 

[westward10]

For a UPS to run for possibly two days you are going to need some serious battery packs.

 

[Avo Mk8]

For a UPS to run for possibly two days you are going to need some serious battery packs.

Agree completely, but I don't think that was the original requirement. The first post uses the phrase "short duration" twice when describing the power outages. The longer period is mentioned in the context of how long the setup stays off because it's tripped and nobody's noticed, or they are away!

 

[westward10]

Got you now.

 

[James]

I think firstly you need to figure out what it is that is tripping.

I would not expect a motor overload to trip because of a short power cut.

however depending on the type of boiler, it may go into "lockout" because the fan or burner blower has stopped.

it may be that just a small ups on the boiler itself will suffice.
if the pumps stop for a few seconds , the boiler may well shut down or reduce its output as the temperature increases but should start up again when it sees the temperature reduce when the pump starts again?

 

[SJD]

I think firstly you need to figure out what it is that is tripping.

I would not expect a motor overload to trip because of a short power cut.

however depending on the type of boiler, it may go into "lockout" because the fan or burner blower has stopped.

it may be that just a small ups on the boiler itself will suffice.
if the pumps stop for a few seconds , the boiler may well shut down or reduce its output as the temperature increases but should start up again when it sees the temperature reduce when the pump starts again?

No, it is power to the whole premises that loses power. It is a somewhat rural location, and prone to power cuts, mostly of a short duration, sometimes longer.

When the power cuts out, the contactors drop out, and when power is restored, someone needs to restart the pumps.

The boiler just restarts when power is restored, except with no water flowing, it then shuts down.

 

[James]

ah, this seems fairly easy to resolve.

There is no requirement for manual starting of pumps, just wire the pump contactors to come on with the boiler time clock.
if there is no time clock then add one.

 

[plugsandsparks]

FWIW. I manage a site with pool pumps etc etc. If grid is lost, there is a 20 second delay before genny powers up. UPS's are used for the internet and internal comms to enable reporting of what is going on. Because the genny is not powerful enough to power all possible loads, certain loads are held off until the grid is restored, this includes the many pool pumps. When grid is restored the pool pumps re-start automatically as they are controlled by manual selector switches , not push button start requests. You could just replace the push buttons with a selector switch - maybe.....
Either way the pool control panel was built by a professional outfit and the pumps always re-started when power is restored.

 

[SJD]

ah, this seems fairly easy to resolve.

There is no requirement for manual starting of pumps, just wire the pump contactors to come on with the boiler time clock.
if there is no time clock then add one.

The pumps have to be started manually for a few reasons, partly safety concerns (plus there is an emergency stop wired in at the pool), and partly because the pumps don't always reliably start (something to do with the pipe arrangements and one of them sometimes getting an airlock). So if they are stopped, someone has to start them and physically check in the pump house they both run.

Hence the site would like to eliminate the number of times they stop (with a UPS).

 

[Mike Johnson]

What safety concerns?
Why the emergency stop?
Pipe arrangements need work?
All the swimming pools I have been involved with re-start automatically once power is restored, it sounds as though the installation needs revising IMO.

 

[SJD]

What safety concerns?
Why the emergency stop?
Pipe arrangements need work?
All the swimming pools I have been involved with re-start automatically once power is restored, it sounds as though the installation needs revising IMO.

Some external safety review recommended adding an emergency stop, I suspect they thought someone might get sucked against a water intake, so one was installed. I've no idea whether this is a realistic concern or not, but not for me to question it!

Yes, I think the pipe arrangements are a problem, some pipework is above the pool and pump water levels. There are also quite a number of valves to allow things like backwashing of filters, filling, emptying. I think not all the pipework is fully water tight (there are minor leaks here and there).

However, the request is for a UPS to work with the system & pipework as it is, there is not the budget to revist these at this time, and beyond my expertise (I don't do anything that involves getting wet). It is a somewhat legacy system with alterations over time.

Possibly putting the pumps, boiler & any related items like dosing & monitoring on the one UPS. Given that the pumps run at approx 2kW, and the rest will takes less than 1kW, the total load is no more than 3kW. It only has to run for a short time for short outages (30 mins, perhaps even less).

My question is for people familiar with UPSs, do I just suggest a UPS rated at 3kW, or do I need to allow somewhat more to cope with pump start-up? Generally there will be mains power when the pumps are started, the UPS is just to keep them running, so possibly 3kW is sufficient?

 

[plugsandsparks]

Any UPS has to be the supply for the pumps, the grid runs behind it. Its the only real way of ensuring there is no interruption. a UPS can also be a grid conditioner and clean up a crappy grid. So your pumps start current will need to go through the UPS..... So any UPS you will need to check their specs for short duration current surge.

 

[Mike Johnson]

This sound like a very amateur bodge up DIY pool, personally it would give me the jitters on what else has been bodged, think I would walk away.

 

[SJD]

Any UPS has to be the supply for the pumps, the grid runs behind it. Its the only real way of ensuring there is no interruption. a UPS can also be a grid conditioner and clean up a crappy grid. So your pumps start current will need to go through the UPS..... So any UPS you will need to check their specs for short duration current surge.

Ahh yes, of course, thanks.