Booster Pump into Combi Boiler? DIY solution?

[Jezclayton]

This would also give me much better flow for my garden, where the hosepipe presently gives out no more than a limp squirt!

So you have 1 bar static pressure and poor flow from the mains cold water. Assuming your mains pressure never rises much above 1 bar, I wouldn't recommend an accumulator in this instance.

The problem you have is as much to do with pipework sizing as pressure. Have you measured the flow rate at the outlet closest to the incoming mains, normally a garden tap or kitchen sink cold tap.?

To cut a long story short, you original idea of boosting the incoming mains is along the right lines . Why not consider a Grundfos Home Booster?:-

http://www.grundfos.co.uk/web/HOMEuk.NSF/MDR/DMAR-6RZKWV?OpenDocument

 

[simond]

Dr Drivel wrote:

Another bathroom changer. You don't know what an accumulator is.

To use Dr Drivels comment earlier, I know what an accumulator is and 1bar is not going to give a satisfactory performance.

The pressure rapidly falls away at 1 bar; the ideal air charge in the bag at the outset is 1.5bar less than static. If you have less than 1.5bar static in the incoming main then you can see this is not going to be achievable.

A large amount of time and money has gone into developing the Mainsboost Charger, which is an accumulator and a low speed, low noise pumpset designed to boost the static charge pressure rather than supply all the water real time. It is designed for situations where the static pressure is below 1.5bar.

This is an expensive solution that works like a standard accumulator on a 3bar main (in other words, superbly). We have installed a number in our area.

If you want cheap and cheerful, a break tank solution is an option. Grundfos make one in a box and call it Homeboost. There are issues with break tanks but it has all been covered here before.

Finally, as the others have said, a small combi will always give a small hot water performance, whatever gets parked behind it.

 

[Agile]

That is a simple package and will do the job although a larger storage tank may better suit him. ( See below ).

Part of his problem at first was that he did not realise the relevance of the very limited hot water flow rate from his combi, just 12 li/min.

The Home Booster is very convenient but quite expensive and I am sure he can put together a system for about a third of that price based on what he has outlined above.

A significantly better system would be his pumped system together with a new unvented hot water cylinder. That could increase the hot water flow rate to say 20 li/min which means a kitchen tap can be used at the same time as the shower.

Tony

 

[GCarnegi]

I did consider the Grundfos home booster system, and I'm sure it would work in many cases. Main reason for not considering it was the price - over a grand plus VAT. Secondly, I'm not sure that it can handle negative head. Either way, too expensive and I have an empty garage attic where a couple of tanks would fit in lovely.

I could look at some stored hot water, but it would have to go in the garage with the other tanks. Sounds like it's getting expensive? Does that mean I'd need to pump both the hot and cold, separately?

I'm wondering if the pipework from the pump to the header tank in the loft, to the boiler back to the hot water tank in the garage and then back upstairs to the shower might be a bit convoluted. - unless you get low hot water tanks (no more than a couple of feet tall, that could fit in the eaves of my loft - ie behind the vertical walls in my loft conversion.

 

[Simonbeasley1]

I have come across this problem recently where client wanted the cylinder removed to house a tumble dryer and washing machine freeing space up in the kitchen.

The flow rate and pressure was poor similar to yours and i advised her against the installation however she wanted the combi. I explained that we could fit but it would have to have tanks and a rather large pump that would feed all cold outlets and the supply to the combi. Please not kitchen tap has to be kept mains cold and not pumped.

Fitted storage tanks that connected via 28mm pipe into a Stuart Turner periphial boostamatic pump approx £250 plus vat this then fed the cold feeds in 22mm pipe around the house and then also into the combi delivering aprox 2.4 bar pressure and 50 litres per minute.

Now combi produce anything up to a max 18litres depending on what combi your have. this one in particular produced around 15 litres. in order to balance up the colds we fitted flow reducers where needed i.e 4 -7 on basin, 15 on bath taps. overall the system worked well and client has extra room in the kitchen.

hope this helps

Simon

 

[BigBurner]

A significantly better system would be his pumped system together with a new unvented hot water cylinder. That could increase the hot water flow rate to say 20 li/min which means a kitchen tap can be used at the same time as the shower.

How would an unvented cylinder increase the flowrate of a pump? Duh!

 

[Agile]

How would an unvented cylinder increase the flowrate of a pump? Duh!

His limitation on hot water flow rate is currently his 28 kW combi giving about 11.7 li/min.

An unvented cylinder will give a flow rate of 20-25 li/min depending on his pump pressure and flow rate and the hot water pipe sizes.

Tony

 

[BigBurner]

Now combi produce anything up to a max 18litres depending on what combi your have.

A number now go to 23-25 litres/min, elimianting the need for stored water cylinders.

 

[BigBurner]

How would an unvented cylinder increase the flowrate of a pump? Duh!

His limitation on hot water flow rate is currently his 28 kW combi giving about 11.7 li/min.

An unvented cylinder will give a flow rate of 20-25 li/min depending on his pump pressure and flow rate and the hot water pipe sizes.

Tony

But unvented cylinders can explode and kill him and his family, cost a fortune to install, take up space and cost an annual service. While a new high flow combi costs no more than the unvented cylinder, more efficient so cheaper run, delivers the flowrate and far less likely to prematurely eliminate his family from this earth.

 

[BigBurner]

A large amount of time and money has gone into developing the Mainsboost Charger, which is an accumulator and a low speed, low noise pumpset designed to boost the static charge pressure rather than supply all the water real time. It is designed for situations where the static pressure is below 1.5bar.

The only drivel is from you. How does this contraption operate? And of course it will be horrendously expensive. How can something so simple take years?

A pressure operated pump with a flow regulator in the pipe set below what the mains delivers can do this (you are not to pump in more than what the mains delivers) ...and no doubt easier and cheaper.

 

[doitall]

Mainsboost demo

 

[BigBurner]

A large amount of time and money has gone into developing the Mainsboost Charger, which is an accumulator and a low speed, low noise pumpset designed to boost the static charge pressure rather than supply all the water real time. It is designed for situations where the static pressure is below 1.5bar.

The only drivel is from you. How does this contraption operate? And of course it will be horrendously expensive. How can something so simple take years?

A pressure operated pump with a flow regulator in the pipe set below what the mains delivers can do this (you are not to pump in more than what the mains delivers so native pressure is not in the mains pipes) ...and no doubt easier and cheaper.

 

[doitall]

The best solution is not often the cheapest BigBurner.

 

[gas4you]

The best solution, as always, is to ignore the drivel given on here by BB/Dr Drivel

 

[Agile]

It surprises me that Diyitall is having a kind of conversation with BB.

Perhaps Diyitall has not noticed there is now an "ignore" button beside all of BB's postings!