Extra 22mm boss on HWC, can I use it for shower pump?

[simongii]

Hi,

I wonder if anyone can answer a question for me. I'm installing a new (larger) HWC for use with a 2 bar shower pump. Plan A was to use a Surrey flange through the normal top outlet for the hot water and have the high priority feed heading to the pump (then to shower and bath) and the other feed to the bathroom sink.

My cylinder came with an extra 22mm boss on the same side as the cold feed in but at the top. I was wondering if and how I could use this as a separate feed for the pump? It looks like where you'd place an Essex flange but this boss has a lip in it which will not allow tube to be pushed all the way in. My understanding is if I take a feed for the pump from the side of the tank I need to have a tube that will roughly reach the centre of the cylinder if viewed from above; with a 45 cut on the tube's end. Is there a special fitting that you use for this? I guess a real Essex flange doesn't have this lip that restricts 22mm tube?

Not sure what else this boss could be used for so will end up blanking it and going with the Surrey but dedicated full bore pumped and non-pumped outlets sounded even better.

Any comments greatly appreciated as usual. Some images attached showing the connections on the HWC.



Simon

 

[simongii]

I've found through further searching that the lip (seems to be called a stop) can be filed away with something like a dremel. Sounds reasonable - anyone else have any experience of doing that?

 

[simond]

The idea is with a Surrey flange is that the water supply comes from an area of the cylinder with few bubbles.

Similarly the side mounted draw off can be used.

Different shower manufacturers have different requirements - which is odd because they are all trying to get round the same propeller cavitation problem - but if you want the pump warranty to be valid, do what they say, not what you think.

Water temperature is very important too, for a number of reasons.

 

[_Ben_]

I have a similar cylinder - Range stainless? In the end just took the shower pump feed direct from the side boss.

I wouldn't like to file the stop down in case the tank's integrity is affected.

 

[Servotech]

It looks to me like it's a secondary return for the hot water (normally used on larger properties like hotels to prevent dead legs).

Don't file the lip off because it's been specially made to take a union (e.g. 22mm Y65).

I can't see any reason why you cannot use it as the hot feed for your power shower though.

Can't see any reason with inserting copper tube into the middle of the cylinder with the end cut at 45 degrees either (pure nonsense).

servotech

 

[dilalio]

Call the tech nr of the cylinder manufacturer... That way you don't risk voiding any warranty!

 

[simongii]

Thanks for the replies all. I looked at the manufacturer instructions and it says either top or side, but does recommend a short length dip pipe like simond advised to get away from any bubbles of air in the HWC.

Yep Ben, that sounds like the one, it's a stainless one. How long have you been running it in that way? I understand air is not great for pumps, but sounds like you haven't had any issues?

Thanks for the reply servotech, I think you're right, filing the lip isn't very smart. But the "birdsmouth" and dip pipe do make sense, albeit how much effect that amount of air actually has in practice I don't know. I've attached the manufacturer's recommendation below.

Thanks dilalio; I found the installation guide rather than call the number but it looks quite explicit in there.

I think I'm left with this decision:
1) Use a Surrey flange from the top and blank the side boss
2) File away the lip at risk of compromising the integrity and warranty of the cylinder
3) Don't use a dip tube and plumb straight from the side boss and compromise the warranty of the pump

As much as I'd love to take advantage of the side boss, it seems it would be silly to risk blowing the warranty (or worse the integrity) of the HWC and pump.

Thanks a lot for the replies though, really appreciate people taking time to help on these forums.

Cheers,

Simon

 

[Agile]

I don't see why any simple connection to the side would risk taking any air at that point.

Nor do I see why any pump maker would have any good reason to not accept that.

Tony

 

[St0rmer66]

The side boss is specifically put on a cylinder for a shower draw off. You'd be silly not to use it IMO. No way air is going to get into the pump through that.

 

[dilalio]

Saves money on buying a Surrey flange to!

As an aside, I have always wondered why they are called Surrey and Essex flanges! Could it be to do with the Counties they have been adopted by??

Think I might try and go have a Google... will report back if I find anything

 

[_Ben_]

Hi,

My pump has been running from the side boss (without any form of dip tube), for about 6 months. Pump is a Turner Monsoon 3 bar.

 

[simongii]

Hi,

Thanks again for the replies.

I think I will just use the side boss then and ignore the requirement to use a dip tube.
I guess heating water does cause bubbles but realistically not many are likely to find their way into my pump. Weirdly the cylinder is at a very slight angle (maybe loses quarter inch from top to bottom) which leans towards the boss in question. I blame it on a cheap spirit level! I was going to find something to shim it level before filling it up completely; but may leave it now to encourage any bubbles away from the boss!

3 bar pump sounds good! Can I ask what set up you have? I have a 40cm square rose and 4 body jets; and quite a large bath; I've used a 210 litre HWC and looking at cold tanks now (probably ~ 70 gal); I'd love to hear what capacities you went for to feed what kind of outlets and if you've found any sizing issues?

Cheers,

simon

 

[Madrab]

If you only have one bathroom and only feeding the shower from the tanks a 50Gal CWSC should be plenty unless you're looking for 45 minute showers , the hot would probably run out before the cold anyway.

Air being forced out of the water by heating can be drawn into the pump causing cavitation at the edges of the impeller blades and over time can destroy them, the side entry tapping should be fine at minimising air draw as the air gathers at the top of the cylinder.

 

[stardanny]

Weirdly the cylinder is at a very slight angle (maybe loses quarter inch from top to bottom) which leans towards the boss in question. I blame it on a cheap spirit level! I was going to find something to shim it level before filling it up completely; but may leave it now to encourage any bubbles away from the boss!

If you keep the cylinder platform, where the cylinder sit, level then that all you need. Foam on cylinder are not always same thickness.

Side boss is fine for pumped shower.

Daniel

 

[_Ben_]

I went for the 180ltr HWC to feed a single shower without side jets.

Its quite powerful, but suits us. I used a new tapping from the cold tank in the loft, staggeringly massive ( for the size of property) and have had no need to upgrade it.

Sizing wise everything seems to have worked out with enough hot water for the two of us. Shower head is smallish at 15cm.