Advice needed for new hot water cylinder configuration please?

[mbc0]

Hi,

I am about to replace my hot water cylinder from a RM 900 X 450 to a Telford 1800 X 450. The first thing I have noticed is there is no secondary tapping on the Telford for the upstairs shower like I have on the RM. I am installing another shower connected to the same pump for our downstairs bathroom and would like some advice on wether or not it is needed? Telford told me they can add a secondary tapping for a couple of quid but he didn't think it would be necessary?

Could I connect the standard top outlet into the shower pump to feed both showers and the rest of the house or would I notice a difference if I connected a secondary tapping to the pump for both showers and the top outlet to the rest of the house?

Many Thanks in advance!

 

[ShaunCorbs]

Yes it's required or a s flange installed

And depends on the rating of your shower pump and are they being used at the same time ?

 

[mbc0]

Hi, thanks for an amazingly quick reply!

I have a Grundfos 3.0 bar twin pump Grundfos 96787466 Regenerative Twin Shower Pump 3.0bar | Shower Pumps | NoLinkingToThis

I am not sure if there is a Surrey Flange, this is something I need to google/understand to be able to answer!

Yes both showers will run at the same time (hence the cylinder upgrade)

Thanks Again!

 

[ShaunCorbs]

Salamander Pumps S Tank Flange Fitting for Hot Water Cylinder 22mm | Shower Pump Accessories | NoLinkingToThis

If you plan to run both I would check your plastic supply tank is round about 80-100 gallons depending on water pressure

And get Telford to install two pump connection

 

[mbc0]

I am concerned about the cold water storage as I am not sure it is big enough. It does not fill very quickly so I have ordered a new part 2 valve to see if it improves and will test it. My Loft hatch is so small I would have to enlarge it to get anything else in, maybe a secondary tank?

Can I ask what a two pump connection is please? do you mean two outlets or a special connection?

Thank you Shaun

 

[ShaunCorbs]

Yes you can combine two or three tanks together, need to do it a special way

And sorry for some reason I thought you were using two pumps

 

[mbc0]

Aha! no just the one pump!

That's great, thank you for the info! I will look into this "Special Way" to add a secondary tank if it becomes an issue after I have fitted the Part 2 Valve

 

[ShaunCorbs]

Only need either a shower pump connection or an s flange then and 22mm feeds

 

[mbc0]

Would this be the best way to feed the shower pump?

Cylinder Config.JPG

 

[ShaunCorbs]

Yes

 

[Welder]

With any pump, ALL manus require you to have TWICE the capacity of your hot water cylinder as cold storage cisterns in a low pressure system.

What this means, is that if you have a 200litre hot water tank, you need cold water in loft of 400litres.

You must also make sure the cold supply to your pump is fed DIRECTLY from the loft tanks. In this case in 22mm copper with FULL BORE isolation.

If not, you run the serious risk of running. out of cold water BEFORE you run out of hot. A dangerous (very) situation.

 

[mbc0]

Thanks for the advice Dave, I can confirm that is how I have plumbed the pump but I will have to understand the cold storage a bit more as I am about to order a 280 litre Cylinder.

 

[Welder]

Basically, both hot & cold to an independent pump should be fed from same tank. This is a safety requirement not fad or fashion. The cold supply to you pump MUST be taken from LOWER than the supply to your hot water cylinder. This so because to remain safe your pump should go run out of hot water first. If your loft tanks are too small, and say your neighbours started watering thier lawns and the tank couldnt fill quickly enough, you must never continue pumping just hot water.
Many people (homeowners to be honest) feel this is overkill. However, most plumbersvwith experience will regal you with true stories of circumstances you simply couldn't make up. Life has a way of killing or maiming the ones you love in a heartbeat. You then spend the rest of your life in heartache.

 

[mbc0]

Grundfos approved my plumbing plan to be used with their pump and also both showers have thermostatic cut off protection so hopefully all good!

 

[Welder]

TBH, I'm not really bothered who did what for whom. My job is to tell it as it is; to provide robust, honest and safe advice based on years of experience of systems and their impacts.
You have but two choices, to act upon that advice or ignore

 

[mbc0]

Advice is why I am here Thanks for all of it from everyone!

Looking into a near 600 litre cold water storage! :-0

 

[ShaunCorbs]

Advice is why I am here Thanks for all of it from everyone!

Looking into a near 600 litre cold water storage! :-0

Why 600l ????

 

[mbc0]

With any pump, ALL manus require you to have TWICE the capacity of your hot water cylinder as cold storage cisterns in a low pressure system.

What this means, is that if you have a 200litre hot water tank, you need cold water in loft of 400litres.

If I were to use Yorkshire Dave's advice I have a 280 litre Cylinder on it's way.

 

[justlead1]

The standard ball valve fitted to CWSC control and fill the cistern over long period, owing to the small orifice that allow mains water into cistern. Using a equilibrium ball valves will deliver say 5 fold and more in the same time as part two valve. This may well help to improve the challenges described.

 

[Welder]

Good point. However the popular ones cannot provide the redq air gap to comply with water regs and so be safe ?

From memory there might be one make that does but its a vary rare beast...