Constant pressure pumps

[Flanners]

Afternoons guys we have just installed a 400ltr solar cylinder on a 37kw Vaillant system boiler. Customer is adding solar thermal in next few months and also underfloor on the whole downstairs.

it is six bedrooms, two en-suites and a main bathroom. They are thinking of adding a wet room downstairs also.

we had 3.1 bar pressure at 16ltrs per minute before we started. From two separate cold mains. We have one dedicated to the cylinder and one to the taps. We also added a secondary loop which it didnt have. we did inform the customer that we may need to add a constant pressure pump to supply water if he wanted all three showers were running at the same time.

everything works fine. You can run two showers perfect and still use all the taps etc. However if he turns on the third shower or adds the wet room he will need to put a pump on if he wants to be able to use everything at the same time.

just wandering if anyone else has installed these or has gotten over a similar situation with an alternative option???

thanks!!

 

[Mike Jackson]

16 l/min is very low for that set up. Your only options are

1. Upgrade the cold main if there is sufficient flow available from the street.

2. Add a booster set, either a stand alone unit like the grundfos home booster or the lowara Resvari and Resfix or a seperate pump fed from a storage cistern.

3. Fit an accumulator.

None of the options will be cheap though.

 

[Flanners]

16 l/min is very low for that set up. Your only options are

1. Upgrade the cold main if there is sufficient flow available from the street.

2. Add a booster set, either a stand alone unit like the grundfos home booster or the lowara Resvari and Resfix or a seperate pump fed from a storage cistern.

3. Fit an accumulator.

None of the options will be cheap though.

Thanks for the reply Mike

i made the customer aware that a stand alone pump, break tank etc may be needed so he is fully prepared to add this to the system. I said he was looking around the £2k mark.

he just wanted to see how it would operate without one first and see if he can live with it for the time being. TBH it works fine until three people need a shower!!

He didn't have much of a choice as he wanted solar thermal and use of multi appliances. The system we fitted him was best for what he wanted. Just need to increase the flow / pressure for him now.

thanks for the recommendations of the pumps also. Ill take a look.

 

[Mike Jackson]

I fitted a resfix and it works really well, gave me in excess of 50 l/min. came out a fair bit cheaper than the Grundfos one as well.

 

[Flanners]

I fitted a resfix and it works really well, gave me in excess of 50 l/min. came out a fair bit cheaper than the Grundfos one as well.

Thanks mike!

how big is the resfix? Could it go in a roof space if I have the flow to feed it??

 

[chris watkins]

I don't disagree that a boosting package may be required in this case, however it should be remembered that unless specifically specified plumbing systems are not designed for all outlets to be working simultaneously, a diversity factor is always applied, otherwise the pipe sizes would be massive & the costs prohibitive.
BS6700 loading units provide this if the form of a design flow rate based on the number of fittings installed.
P.S. Booster pumps in lofts are never a good idea due to noise & vibrations.

 

[Mike Jackson]

You'd struggle. Imagine something with the footprint of a washing machine and about 4 foot high.