installing a shower pump in flat question

[nickdesign]

Hi Guys,

am looking to install a single pump on the hot supply in our bathroom for a shower.

want to check it wont cause any problems.

we live in a low-rise block of flats, ground, first and second floors.


The hot water system is gravity fed - we have a huge cold water tank in the roof space, which runs all the way down to the basement when it is heated by our oil fired boilers and then goes on to the clorifiers. It is then piped up the building via various feeds using the force of the downwards gravity from the roofspace,.

We have two hot water feeds in our flat, one for the bathroom and one for the kitchen.

we are on the first floor so have one flat below us and one above us., the hot water pipe runs floor to ceiling in our airing cuboard - which only supplies the bathroom in our flat plus the one above and below, with a return downwards pipe to complete circuits for the towel rail and hall radiator, which both run off the hot water system.

We had some plumbing work done and as part of that have a new direct feed from the hot water supply pipe in the airing cuboard - the plan is to run a pump on this supply to feed a mixer shower.

One person I have spoken to says this will not cause any problems and that the pump should not starve the flat above us of hot water as there is enough supply there.

I want to check what you guys think - if i use a pump am i going to create a demand that then drops the water pressure for the flat above and below?

 

[nickdesign]

bump

 

[Technotim]

You would need to supply with the pump fitted next to the cylinder (clorifier) pumping to the shower (as pretty much all pumps are designed to push water not drag it) an independant pipe to not effect your neibours. It sounds like there would be a secondary return on the system (a small circulating pump) which could also cause some problems if you used that supply.

 

[nickdesign]

Hi Tim, as i understood it the pump could be sited in the flat as even though the boilers are in the basement the cold water supply tank is in the roof space, which supplies the 'push' for the gravity fed system?

I would not be able to have an independent feed - does this mean a pump would definitely have an affect on the other users? There is no secondary pump - the return is circulated purely by the gravity of the downward cold supply

 

[Technotim]

All pump manufacturers would want the pump within 3 meters of the hot water cylinder, if you really want a pump then look at the pipe sizing if the supply pipe is 28mm going to the flats above and below then if you use a small brass ended pump you should not have too much effect on your neibours and you should get duarbility from the pump as it would be regenerative and they are much more forgiving in this kind of situation.

The incoming water temperature can also be a problem as when you have common water storage you generally store the water at higher temperatures to ensure that all property's get the water at the desired temperature. there is only one pump that I know of that could go up to 70 degrees and fits the criteriahttp://www.tapstore.com/acatalog/Turbo_1_Single_Pump_1_0bar.html
Do beware the manufacturers will not guantee the product when installed not to the installation instructions.

 

[nickdesign]

Hi Tim,

thanks for your reply.

what do you mean by a small brass ended pump? also not sure i understand what you mean about it being regenerative - sorry for being thick!!

I am pretty sure the pipe running from floor to ceiling suppling the flats is 28mm at least.

The temperature I've been told never exceeds 65 degrees.

Do you have any recommendations for the type of pump?

thanks!

 

[Technotim]

we use two types of pumps a, Regenerative and b, centrifugal that is the discription of the type of impellor,

regenerative is like a watermill it takes its water in one side of the impellor and throws it out the other side they tend to be less fussy about the install critiria and are much more durable.

Centrifugal Pumps are where the water enters the pump at the end of the impellor and is thrown to the out side to create the flow and pressure, they are not so durable and can suffer from cavitation a lot easier due to air in the water system and loads more reasons that I would have to write a book about to explain, there main benefit is they are quieter and give a better flow rate.

if you look at the first link of the regenerative pump i posted you will see the connections laying side by side and if you look at the image in the link below you will see you have one connection on the top (outlet) and one at the end of the pump (inlet). so that is centrifugal.http://www.new-team-pumps.co.uk/Newteam-Duraspeed-Shower-Pumps.html.

I would use the one in the first link I have it here in my office its is quiet for a brass ended pump and the design means it will last for ever. it does not have a massive flow but it will certainly give you a boost to a good shower and has the ability to run basin and bath taps as well.

remember the larger the pump the more likely that you will effect other people in the building.

 

[nickdesign]

thanks for your patience!!

so the link you've given will work with our setup - and i'm assuming that pump produced 1 bar output pressure? - would the cold pressure (mains) need to be reduced to 1 bar also? as i read somewhere to mix a warm water temp it is roughtly 2 lots cold to 1 lot of hot - so could the cold be 2 bar?

thanks!

 

[nickdesign]

also can i clarify having explained our setup that i deffo need a positive head pump?

thanks

 

[nickdesign]

main hot water pipe running through the flat is 40mm / 1.5"

is that good? what sort of output pump should i fit?

 

[Technotim]

so the link you've given will work with our setup - and i'm assuming that pump produced 1 bar output pressure? - would the cold pressure (mains) need to be reduced to 1 bar also? as i read somewhere to mix a warm water temp it is roughtly 2 lots cold to 1 lot of hot - so could the cold be 2 bar?

The Turbo 1 will be fine, yes the pressure will be 1.0 bar as a static pressure. you could use a pressure equalizing valve these will take the highest pressure and reduce to the lower pressure, but if you have access to the pipe work then you can suck and see approach slight imbalances normally work but your mains will vary depending on how many others flats use water at the same time, equalizing valve will always work.
http://www.tapstore.com/acatalog/Pressure_Equalising_Valve.html

also can i clarify having explained our setup that i deffo need a positive head pump?

Yes unless you are fitting a Steam shower.

main hot water pipe running through the flat is 40mm / 1.5"

is that good? what sort of output pump should i fit?

that is good you could possibly use a 2.0bar pump, now if you do have issues with other property's by using a 2.0 bar version you can always slow the flow down by using flow restrictor costing a few pounds but would get a better performance all round, and would match the mains pressure better.

Check that the shower you buy has a non return valve fitted if not fit a 22mm non return valve to the outlet of the pump.