Best practices for water pump purchase

[Bassosa]

We're about to purchase two water pumps which will supply 8 hotel rooms each. The water pumps are underground and water needs to delivered to the ground floor, as well as second and third floor. 

 

What are things to look out for when buying?

 

So far, I've noticed that it needs to be "constant pressure" pump but what do I do to prevent sudden pressure changes in the system when say someone decided to have a shower? Is that what a pressure tank is for?

Also, is getting inverter technology recommended? As our pumps serve many outlets I expect much use, so I'm leaning towards getting the more expensive inverter pumps.

Does inverter also mean less "shock loading" on the system. It is my understanding that a normal water pump is either on or off, so more shockloading as the pump cycles on. Does an inverter alleviate this?

 

Thanks for your feedback.

[Artisi]

Buy Grundfos pumps, very well enginered and quality manufacture, a wide range of types and models, more expensive but well worth it.

[canopy]

13 minutes ago, Bassosa said:

So far, I've noticed that it needs to be "constant pressure" pump but what do I do to prevent sudden pressure changes in the system when say someone decided to have a shower? Is that what a pressure tank is for?

A lot of them come with integrated pressure tanks. This tank will dampen the pressure increase when the pump turns on. A gradual pressure increase will occur until the water pressure builds up to your high pressure limit setting. You can optionally add a big pressure tank to the system to reduce pump on/off cycling frequency. A company like grundfos will listen to your requirements and recommend a suitable pump and accessories.

 

[sometimewoodworker]

3 hours ago, Bassosa said:

So far, I've noticed that it needs to be "constant pressure" pump but what do I do to prevent sudden pressure changes in the system when say someone decided to have a shower? Is that what a pressure tank is for?

Also, is getting inverter technology recommended? As our pumps serve many outlets I expect much use, so I'm leaning towards getting the more expensive inverter pumps.

Does inverter also mean less "shock loading" on the system. It is my understanding that a normal water pump is either on or off, so more shockloading as the pump cycles on. Does an inverter alleviate this?

Yes inverters will avoid shock loading. I suggest the same as I have as it is probably perfect for your case, you can also increase the pressure on the pump if you find it not enough or too much.

the guarantee is superb, one year from installing ours developed a problem and when bringing it in (because 50km from the dealer) it was instantly replaced with a new one.

[VocalNeal]

How many rooms on each floor? Ground floor Kitchen? Bar? 

 

Are all floors connected to the same pump or have separate piping? 

 

Hot or cold water.

 

Just for example. 

 

Buy local that way any repairs etc will be easier

 

Just thinking that most commercial premises have a water tank on the roof. 

 

 

 

 

Edited October 22, 2019 by VocalNeal

[Fruit Trader]

Talk to a local pump supplier or plumber with commercial experience. Avoid odd job plumbers.

 

Most businesses including ours who depend on reliable water pumping use multi centrifugal pump systems with suitably sized pressure tank. Some systems will use multiple pumps as demand changes while others will operate pumps on a duty cycle leaving redundant backup.

 

These reliable easy to repair systems are available all around Thailand in various sizes and flavours. Smaller systems (<= 1hp) are often custom built on site. 

 

The aim is to provide fail backup to the whole service and build using components that are easily sourced.

Example pump  stations. Available .5hp - xxhp

 

[Bassosa]

21 hours ago, Fruit Trader said:

Talk to a local pump supplier or plumber with commercial experience. Avoid odd job plumbers.

 

Most businesses including ours who depend on reliable water pumping use multi centrifugal pump systems with suitably sized pressure tank. Some systems will use multiple pumps as demand changes while others will operate pumps on a duty cycle leaving redundant backup.

 

These reliable easy to repair systems are available all around Thailand in various sizes and flavours. Smaller systems (<= 1hp) are often custom built on site. 

 

The aim is to provide fail backup to the whole service and build using components that are easily sourced.

Example pump  stations. Available .5hp - xxhp

 

In the meantime, we spoke to some technicians and are indeed considering a similar system as pictured by you. It seems to be the best way to achieve guaranteed water pressure wherever you are in the building, irrespective of load. 

 

They do tell us that the pump should be very close to the water tank. Is that true? In our case that is not that convenient.

We need something proper because our building is multi-story and the builder only installed 1" water pipes even though we made it clear from the beginning that we want decent water pressure throughout the building.

None of the technicians we spoke to so far, will tell us what water pressure we can achieve up high. They just commit to water pressure "at the pump". 4 bar with probably 3 bar up high is what they think.

We're talking to Grundfos but were also offered a Espa system. Apparently made in Spain? Does anyone have any experience with this brand?

Edited October 23, 2019 by Bassosa

[Fruit Trader]

2 hours ago, Bassosa said:

They do tell us that the pump should be very close to the water tank. Is that true? In our case that is not that convenient.

Stock tanks are best located close to the pumps but its not essential. To determine feed line size, your technician should first survey to find stock tank distance and location above or below pump inlet ports.

 

1" water pipes can service many rooms on a single floor. Problems start when a 1" pipe is in series through several floors. 

Each floor should have its own line from ground or off a main riser.

[sometimewoodworker]

@VocalNeal said a rooftop tank with a pump by it is almost certainly going to give the best pressure. The hitachi pumps shown above usually give a maximum of about 2.8 bar and that is going to be plenty if pumped down from the roof. If you want higher then the Grundfos will go up to at least 4 bar over inlet pressure 

 

 

[Bassosa]

Just now, sometimewoodworker said:

@VocalNeal said a rooftop tank with a pump by it is almost certainly going to give the best pressure. The hitachi pumps shown above usually give a maximum of about 2.8 bar and that is going to be plenty if pumped down from the roof. If you want higher then the Grundfos will go up to at least 4 bar over inlet pressure 

 

 

 We weren't able to have a rooftop tank unf.

[RideJocky]

You might consider installing a regulator on the ground and first floor if you want decent flow on the second floor on the cheap.


Sent from my iPhone using Thaivisa Connect

[Artisi]

1 hour ago, RideJocky said:

You might consider installing a regulator on the ground and first floor if you want decent flow on the second floor on the cheap.


Sent from my iPhone using Thaivisa Connect

Flow regulators are available for fitting to each tap / shower outlet, this will assist in controlling outlets on the lower level. 

[Bassosa]

11 minutes ago, Artisi said:

Flow regulators are available for fitting to each tap / shower outlet, this will assist in controlling outlets on the lower level. 

Do you mean to control (potentially) excessively high water pressure on the lower levels?

Edited October 24, 2019 by Bassosa

[Artisi]

45 minutes ago, Bassosa said:

Do you mean to control (potentially) excessively high water pressure on the lower levels?

Mainly control flow which is your main concern so as to ensure there is sufficient flow at the second level and furthest point from the pump at the pressure you elect. 

 

Actually your "problem" is not a problem to someone who has the necessary detail on hand and knows how to use it. 

There is detail available to establish the necessary flowrate for your project based on the number of rooms, and the number of occupants. You know the height from the source to the highest point, you know the maximum pipe run, you know the pipe diameter and with flow restricters you can calculate the maximum flow demand at the pressure you want at the outlets. 

After sorting out the flow rate and head (pressure) required at the pump discharge you can then look at selecting the necessary pump/s.

With all the detail to hand, probably a 10 minute exercise. 

It's 20 years since undertaking a calculation like this which I would be happy to help with, but unfortunately I no longer have the detail available to do it. 

Edited October 24, 2019 by Artisi

[Bassosa]

1 minute ago, Artisi said:

Mainly control flow which is your main concern so as to ensure there is sufficient flow at the second level and furthest point from the pump. 

 

Actually your "problem" is not a problem to someone who has the necessary detail on hand and knows how to use it. 

There is detail available to establish the necessary flowrate for your project based on the number of rooms, and the number of occupants. You know the height from the source to the highest point, you know the maximum pipe run, you know the pipe diameter and with flow restricters you can calculate the maximum flow demand at the pressure you want at the outlets. 

After sorting out the flow rate and head (pressure) required at the pump discharge you can then look at selecting the necessary pump/s.

With all the detail to hand, probably a 10 minute exercise. 

It's 20 years since undertaking a calculation like this which I would be happy to help with, but unfortunately I no longer have the detail available to do it. 

Thanks for your comment.

I will ask the people bidding for the gig to provide the calculation once we proceed a little further into the project and they have more insight into the situation. Seems like a good exercise to cut the wheat from the chaff.

[sometimewoodworker]

1 hour ago, Bassosa said:

Seems like a good exercise to cut the wheat from the chaff.

Good luck finding any wheat ???? 

[tjo o tjim]

Really the best solution for here is to pump to a tank on the roof, and then have supplemental pumps on the roof for pressurization, especially if the water lines are undersized.  You don’t want to fight gravity and flow on the same run if the pipes are small.

[Artisi]

16 minutes ago, tjo o tjim said:

Really the best solution for here is to pump to a tank on the roof, and then have supplemental pumps on the roof for pressurization, especially if the water lines are undersized.  You don’t want to fight gravity and flow on the same run if the pipes are small.

For an 8 room, 2 level building a roof mounted tank is not really necessary, although possible it just doubles up on pump and control equipment. 

[saengd]

One inch pipework over a long distance will lead to high levels of friction loss, by the time you try to feed the outlets at the end of the chain the flow rate will be very low. Consider trying to increase pipe size wherever possible, 1.5 inch is optimal.

 

 

[saengd]

OK so you don't know what friction loss is:

 

http://www.pumpscout.com/articles-expert-advice/how-to-minimize-friction-losses-with-aodd-pumps-aid654.html

 

https://frictionlosscalculator.com/tables/one-inch/

 

[Artisi]

10 minutes ago, saengd said:

OK so you don't know what friction loss is:

 

http://www.pumpscout.com/articles-expert-advice/how-to-minimize-friction-losses-with-aodd-pumps-aid654.html

 

https://frictionlosscalculator.com/tables/one-inch/

 

Useless, it's fire-hose losses. Search PVC pipe for accurate data. 

 

[saengd]

31 minutes ago, Artisi said:

Useless, it's fire-hose losses. Search PVC pipe for accurate data. 

 

It doesn't matter too much what the pipe is made from although the smoother the pipe wall the lower the rate of loss, that said the size of the pipe is the main issue. BTW was not aimed at you specifically, it was more towards another poster who posted a confused smiley so I though I would provide additional info. But since you asked, here's PVC pipe friction loss tables: https://www.engineeringtoolbox.com/pvc-pipes-friction-loss-d_802.html

Edited October 25, 2019 by saengd

[bankruatsteve]

2 hours ago, saengd said:

One inch pipework over a long distance will lead to high levels of friction loss,

The caption says "Confused" but to me it's more of a "Huh?"  You didn't quantify "long distance" or "high levels" but that statement just seems absurd to me.  I'm not qualified to contradict but when most (?) homes in Thailand have 1/2" incomer and a plethora of 90 degree joints without "friction loss" issues, that makes me think "Huh?".  A 1" incomer and risers would be my preference but 1-1/2" seems superfluous  IMO

[saengd]

42 minutes ago, bankruatsteve said:

The caption says "Confused" but to me it's more of a "Huh?"  You didn't quantify "long distance" or "high levels" but that statement just seems absurd to me.  I'm not qualified to contradict but when most (?) homes in Thailand have 1/2" incomer and a plethora of 90 degree joints without "friction loss" issues, that makes me think "Huh?".  A 1" incomer and risers would be my preference but 1-1/2" seems superfluous  IMO

Fair enough, let me try and explain. The OP says he's plumbing a three storey hotel for water supply, I can only begin to guess at the length of piping but I guess it's somewhere around 50 metres, I may be wildly under on this point. Half inch pipe along with all the 90 degree bends that Thai plumbers use will soon result in loss of flow and friction loss (FL) is mainly responsible for this. By increasing the pipe diameter on the long runs he can reduce FL substantially without trying to compensate expensively at the pump level. In a regular three bed house the problem of FL is not as noticeable because of the scale and number of outlets. But when you start to talk about a hotel with multiple simultaneous outlets the problem will be noticable.

 

I'm no expert in this but I did get something of an education in the subject when I installed a complex sprinkler system. The backbone, from the well/pump to the end was about 110 metres and there are 13 sprinkler heads. Using one inch pipe means the last sprinkler head can only be operated on its own! By upgrading the backbone to 2 inch pipe I can now operate most heads simultaneously and my dependency is now the well refresh rate rather than flow.

 

Some useful links I came across which may help others: 

 

https://southernswater.com.au/why-does-the-size-of-your-pipe-matter/

 

https://beast5.in/how-to-select-submersible-pump-for-borewell/#How_to_Select_Submersible_Pump_for_Borewell_Buying_Guide

(some sections are useful but not all)

 

https://www.irrigationtutorials.com/basic-pump-system-hydraulics/

This one is extensive and excellent, you may need to reload the page to get the page to load, this is the A-Z of hydraulics..

Edited October 25, 2019 by saengd

[saengd]

One more point. If the hotel is not using roof top gravity feed, the total head requirement for three storeys is likely to be over 15 metres (?). That being the case it must be borderline whether a standard centrifugal pump can manage that. 

[Bassosa]

Thanks again for the comments.

 

The highest point in the building is approx 12 meters. Unfortunately we weren't able to install tanks on top of the building, it's a renovation project with many restraints.

 

One of the guys we have quoting for the job showed me a friction chart and indeed, friction loss is a huge issue with 1 inch pipes. 1 1/4 inch pipes would've been SO much better, but our builder, in his infinite wisdom went for 1 inch everywhere.

 

Mai bpen rai.

 

In the meantime quotes are trickling in and the variations in price are staggering. Grundfos want to do a booster pump setup with variable speed (Hydro Multi-B ) with two pumps and two inverters for about 200k but we also have guys suggesting we install 2 "simple" Espa Prisma 750kw pumps for about 40k and be done with it.

What justifies the price difference I wonder?

PS. Comments about regulators on the ground floor duly noted. Will look into that.

 

Edited October 25, 2019 by Bassosa

[Artisi]

3 minutes ago, Bassosa said:

Thanks again for the comments.

 

The highest point in the building is approx 12 meters. Unfortunately we weren't able to install tanks on top of the building, it's a renovation project with many restraints.

 

One of the guys we have quoting for the job showed me a friction chart and indeed, friction loss is a huge issue with 1 inch pipes. 1 1/4 inch pipes would've been SO much better, but our builder, in his infinite wisdom went for 1 inch everywhere.

 

Mai bpen rai.

 

In the meantime quotes are trickling in and the variations in price are staggering. Grundfos want to do a booster pump setup with variable speed (Hydro Multi-B ) with two pumps and two inverters for about 200k but we also have guys suggesting we install 2 "simple" Espa Prisma 750kw pumps for about 40k and be done with it.

What justifies the price difference I wonder?

PS. Comments about regulators on the ground floor duly noted. Will look into that.

 

What is the longest run of pipe, from the pump to the furthest discharge point. 

The Espa aren't 750kw, maybe 750w.

Is the Grundfos quote from Grundfos or an agent, it certainly sounds way over the top? 

 

[saengd]

9 minutes ago, Bassosa said:

Thanks again for the comments.

 

The highest point in the building is approx 12 meters. Unfortunately we weren't able to install tanks on top of the building, it's a renovation project with many restraints.

 

One of the guys we have quoting for the job showed me a friction chart and indeed, friction loss is a huge issue with 1 inch pipes. 1 1/4 inch pipes would've been SO much better, but our builder, in his infinite wisdom went for 1 inch everywhere.

 

Mai bpen rai.

 

In the meantime quotes are trickling in and the variations in price are staggering. Grundfos want to do a booster pump setup with variable speed (Hydro Multi-B ) with two pumps and two inverters for about 200k but we also have guys suggesting we install 2 "simple" Espa Prisma 750kw pumps for about 40k and be done with it.

What justifies the price difference I wonder?

PS. Comments about regulators on the ground floor duly noted. Will look into that.

 

From what I have seen Grundfos and Franklin tend to be the two highest price labels on the market, what makes them so I have no idea. What I do know is that I went for two lesser names and I've been extremely happy with their performance and reliability for the past five years, pehrpa take a look at Saxon and Lowara. 

 

It's an interesting exercise trying to size pumps for a hotel, I guess you go about it in the same way as any other hydraulics project....determine the average flow rate that is need, (presumably this is per room then add them together), determine total head, calculate friction loss and after all that I imagine you must be up somewhere in the area of a 2 kw pump, dunno, I'm out of my deapth here. But Id know that variable speed pumps is the technology that is being touted as the solution to many hydraulics related problems, perhaps that's why.

[saengd]

If not possible to instal a water storage tank on the roof, perhaps a smaller header tank might be beneficial with a pressure switch to activate the pump? 

 

Also, maximum pull on a standard centrifugal pump is 9 metres, beyond that you're into booster pumps staged pumps or different pump technology.

Edited October 25, 2019 by saengd

[CGW]

41 minutes ago, Bassosa said:

friction loss is a huge issue with 1 inch pipes. 1 1/4 inch pipes would've been SO much better, but our builder, in his infinite wisdom went for 1 inch everywhere.

Your over complicating it IMO, 1" should be more than ample, sure P/L gets lower with larger pipe, static pressure will be the same though, the P/L will only be apparent when water is flowing, your never going to have "full" flow through all piping.

The 1" pipe will be downsized to 1/2" at terminations also.