New quooker reducing the flow of the hot water

silvercar

I just want to check if what the plumber says is reasonable. Having a new kitchen and as part of it we have a quooker tap installed on the kitchen sink. 

We also have a sink in a utility room, so can compare the flow rates. The hot water comes from a non-combi boiler, the hot water tank is downstairs, its base about 1m off the ground. 

The water pressure on the cold water is good, the water pressure on the hot water (not the boiling quooker’d water) is noticeably weak and takes an age to get hot. In the utility room, the water pressure is not brilliant but better than on the tap that has the quooker on it. The plumber says it’s because the quooker is on that tap, but I don’t understand why that makes a different difference to the hot water only. 

Grateful for any insights.

grumbler

The hot water (tank) pressure is the same everywhere on the ground floor. The flow depends on the plumbing and on the tap. Some taps are desined for low pressure, some are designed only for mains (high) pressure. If this "quooker" is designed for mains pressure hot water supply, and if in the past you didn't have this problem, then your plumber is probably right.

ETA:  in 

Facts and figures

  I see minimum pressure 2 bar and recommended 2-4 bar for both hot and cold water supplies. With vented hot water tank in a two-storey house the pressure is less than 1 bar.

ThisIsWeird

silvercar said:

I just want to check if what the plumber says is reasonable. Having a new kitchen and as part of it we have a quooker tap installed on the kitchen sink. 

We also have a sink in a utility room, so can compare the flow rates. The hot water comes from a non-combi boiler, the hot water tank is downstairs, its base about 1m off the ground. 

The water pressure on the cold water is good, the water pressure on the hot water (not the boiling quooker’d water) is noticeably weak and takes an age to get hot. In the utility room, the water pressure is not brilliant but better than on the tap that has the quooker on it. The plumber says it’s because the quooker is on that tap, but I don’t understand why that makes a different difference to the hot water only. 

Grateful for any insights.

Hi, Silver.

Likely as Grumbie says. This bit is key; "The hot water comes from a non-combi boiler, the hot water tank is downstairs, its base about 1m off the ground."

Is this hot tank 'vented' or 'unvented'? I suspect the former - you'll have a CWS (cold storage supply) tank in the loft?

If so, you have a 'low pressure' system, so the water will be delivered without much oomph behind it. That's ok provided the pipes are unrestricted. If your tap is, however, designed for 'mains' pressure use - ie 'high pressure system' - then it could very well be restrictive, having small internal bores (or else too much water could gush out too quickly).

So, what type of system do you have - vented or unvent? And - look up your tap - what type of system is it designed for?

Oh, and the cold kitchen tap pressure is good, because that comes direct from the mains = 'high pressure'. And the hot takes an age to come through the kitchen tap because the flow rate is so low&slow.

In short, it looks as tho' you have the wrong tap for your system. Solutions? I guess you could fit a gentle pump on the hot pipe that will provide a nice boost? Or, change your main kitchen tap for a low pressure type, and a separate quooker. If you go this route, you may wish to tweak down the cold mains isolator to the tap to reduce the cold flow a bit, to make it 'similarish' to the hot's. Bear in mind, tho', that even if you fit a low pressure tap, it's still unlikely to be 'great', as your ute's is also a bit pants.

Grundfos used to make a really nice 'booster' pump that wasn't overkill, based on its CH circulating pump! I'll try and find one, but - when installed correctly - they give a 'natural' boost to the flow, are very quiet in use, and come on automatically. I think that could be the best solution. They increase the flow pressure by something like 0.75 bar, so nothing stupid like a shower pump. If fitted in the right place, it'll also give your utility hot, and others, a nice kick too.

ThisIsWeird

This is the baby: https://www.toolstation.com/grundfos-upa-15-90n-home-booster-pump/p71846

Pricey, but I managed to get a couple of these on t'Bay a few years back for my bro to boost his hot and cold gravity supplies. Really effective - no stupid giant pump firing up with a thrummmm. BUT, the plumber installed them incorrectly, so one burned out when it kept on running after his tank was dry! It needs plumbing in 'upwards' - the instructions are very clear.

I'd suggest that this, or a very similar unit, could be your best answer. It should help your hot water from every tap. Bear in mind, tho', that your other 'colds' - other than your sink - could also be 'gravity'/vented, so will now be weaker than the hots!

Have a chat with your plumber

ThisIsWeird

Cheeky with their 'new other' description - it isn't - but still perhaps cheap enough for a punt to see if it's the answer? Ask Qs such as age, where bought, receipt provided? (Could still be under warranty).

(If it doesn't sell quickly, perhaps try a sub-£100 offer?)

https://www.ebay.co.uk/itm/296085548774?

'New': https://www.ebay.co.uk/itm/325430738875? £230. But again check any warranty?

Provided these are fitted correctly, they should be reliable - the same internals often last for decades in many CH systems.

silvercar

Thanks all.

yes, it would be vented as we do have CWS in the loft.

I was just puzzled as to why this hot tap was slower than the utility room hot tap, when they both get their feed from the same route. It seems adding the quooker has slowed the hot tap down and I don’t know why.

I want the 3 in 1 quooker, so a separate tap isn’t the answer. A pump may be the answer, but it may be something we live with, especially as we can get a mix of boiling water from the quooker and cold water into the sink, rather than use the hot water feed.

ThisIsWeird

silvercar said:

Thanks all.
yes, it would be vented as we do have CWS in the loft. Ok, that explains it.

I was just puzzled as to why this hot tap was slower than the utility room hot tap, when they both get their feed from the same route. It seems adding the quooker has slowed the hot tap down and I don’t know why. Because the Quooker its designed for high pressure systems, as I explained.

I want the 3 in 1 quooker, so a separate tap isn’t the answer. Cool - that narrows down the options to one. A pump may be the answer, almost certainly is... but it may be something we live with, especially as we can get a mix of boiling water from the quooker and cold water into the sink, rather than use the hot water feed. WOW! :-)

Replies in bold.

This 'Quooker' cost you how much? I'm guessing around onethousandpounds? And you love it so much that you are prepared to live with a defunct hot water supply, a supply that's already been heated and is sitting pointlessly in a hot tank, begging to be used, but - pah! - it just ain't coming out fast enough?

So, you'll spend how long blending the pitiful flow of boiling water from your Quook, heated by probably the most expensive form of domestic energy available, instead of installing a ~£100-odd pump that'll cost zilch to run, and will transform your whole domestic HW supply to all your taps?

Yeah, fair enough.

ON PLANET ZORG! :-)

TELLIT01

I presume the Quooker has only a cold water feed and it's own heater to produce the hot water.  If that is the case the flow will be slower as it takes time to heat, in much the same way that hot water from a combi boiler has a slower flow than a direct fed mains cold water tap.

grumbler

silvercar said:

I was just puzzled as to why this hot tap was slower than the utility room hot tap, when they both get their feed from the same route. It seems adding the quooker has slowed the hot tap down and I don’t know why.

Do you mean replacing (the old tap(s) with quooker), not adding? A big difference...

silvercar

TELLIT01 said:

I presume the Quooker has only a cold water feed and its own heater to produce the hot water.  If that is the case the flow will be slower as it takes time to heat, in much the same way that hot water from a combi boiler has a slower flow than a direct fed mains cold water tap.

The boiling water from the quooker is at a good pressure, it is the hot water through the boiler, via the hot water tank, that is a low pressure.

silvercar

ThisIsWeird said:

silvercar said:

Thanks all.
yes, it would be vented as we do have CWS in the loft. Ok, that explains it.

I was just puzzled as to why this hot tap was slower than the utility room hot tap, when they both get their feed from the same route. It seems adding the quooker has slowed the hot tap down and I don’t know why. Because the Quooker its designed for high pressure systems, as I explained.

I want the 3 in 1 quooker, so a separate tap isn’t the answer. Cool - that narrows down the options to one. A pump may be the answer, almost certainly is... but it may be something we live with, especially as we can get a mix of boiling water from the quooker and cold water into the sink, rather than use the hot water feed. WOW! :-)

Replies in bold.

This 'Quooker' cost you how much? I'm guessing around onethousandpounds? And you love it so much that you are prepared to live with a defunct hot water supply, a supply that's already been heated and is sitting pointlessly in a hot tank, begging to be used, but - pah! - it just ain't coming out fast enough?

So, you'll spend how long blending the pitiful flow of boiling water from your Quook, heated by probably the most expensive form of domestic energy available, instead of installing a ~£100-odd pump that'll cost zilch to run, and will transform your whole domestic HW supply to all your taps?

Yeah, fair enough.

ON PLANET ZORG! :-)

Yes, about £1k, but it’s sunk money as it’s spent and part of the kitchen refurb. The flow of boiling water from the quooker is good.

Now I’m confused, it is the hot water to this kitchen tap that is slower than other hot water taps in the house that I’m trying to understand, not the hot water feed in general.