Grundfos Home Booster Questions

[jayc89]

Our water supply struggles when more than one outlet's used (showers/baths). It was measured at 3 bar static, 1.1 bar working and 12 LPM at the kitchen sink. Gas boiler, unvented cylinder. 

 

I'm considering a Grundfos Home Booster system, which comes in either a 3 bar or 4.5 bar model and can supply up to 30 LPM, which should be more than enough for us. We already have a multi-bloc in front of the UVC which is limiting the incoming mains pressure to 3 bar. If I was to plumb a 4.5 bar version in ahead of the multi-bloc would it attempted to main 3 bar pressure whilst outlets were open up to a max of 4.5 bar? So as well as providing much better flow, should also provide much better working pressure too?

[ProDave]

Why not a big accumulator on the mains input?

 

[jayc89]

13 minutes ago, ProDave said:

Why not a big accumulator on the mains input?

 

 

Something like this? https://www.salamanderpumps.co.uk/products/mainsbooster/accuboost-tanks/accuboost-330l-pumped/?

It would provide more water, and be cheaper. Presumably there would be no improvement to working pressure when using one though, and I was hopefully that a Home Booster would also help there too. 

[SimonD]

1 hour ago, jayc89 said:

Our water supply struggles when more than one outlet's used (showers/baths). It was measured at 3 bar static, 1.1 bar working and 12 LPM at the kitchen sink. Gas boiler, unvented cylinder. 

 

I'm considering a Grundfos Home Booster system, which comes in either a 3 bar or 4.5 bar model and can supply up to 30 LPM, which should be more than enough for us. We already have a multi-bloc in front of the UVC which is limiting the incoming mains pressure to 3 bar. If I was to plumb a 4.5 bar version in ahead of the multi-bloc would it attempted to main 3 bar pressure whilst outlets were open up to a max of 4.5 bar? So as well as providing much better flow, should also provide much better working pressure too?

 

Pressure and flow are completely different things. Increasing pressure does not necessarily increase flow. However, the main issue is that your installer should never have installed an UVC with those kinds of figures - it was never going to work very well.

 

The water regulations also don't permit the use of a booster of more then 12l/min directly connected to the mains, so if you want to boost flow above this you have to have a break tank installed, so some sort of accumulator or a cold water storage tank with a pump.

[jayc89]

9 minutes ago, SimonD said:

 

Pressure and flow are completely different things. Increasing pressure does not necessarily increase flow. However, the main issue is that your installer should never have installed an UVC with those kinds of figures - it was never going to work very well.

 

The water regulations also don't permit the use of a booster of more then 12l/min directly connected to the mains, so if you want to boost flow above this you have to have a break tank installed, so some sort of accumulator or a cold water storage tank with a pump.

 

My understanding was that's what a Home Booster did; acted as a breaker tank and supplied a cold feed via a pump to both increase pressure and flow, which is where my original question came from. I also thought I'd need a separate break tank if I was to use a standalone accumulator (like the Salamander linked above), like you say. Although the Salamander docs do suggest that, if the tank's empty, it will only supply at a rate of 12l/min (opposed to whatever it boosts to when full), which, I think, would make it compliant with not needing a break tank in front of it?

Edited September 9, 2023 by jayc89

[markocosic]

10 hours ago, jayc89 said:

Something like this? https://www.salamanderpumps.co.uk/products/mainsbooster/accuboost-tanks/accuboost-330l-pumped/?

 

61 dBa...

[jayc89]

3 hours ago, markocosic said:

 

61 dBa...

 

The Home Booster is similar too, I assumed anything pumped would be. It'd be within a "room" in our loft space so it'd be sitting on top of 400mm of loose cellulose (40kg/m3) then 22mm P5 Caberdek, and I could also get some sort of anti-vibration mat too so I'm hopeful the noise wouldn't be a massive problem. 

 

Alternatively, we have a lean-to on the opposite side of our utility wall so we could fit something in there too, which would have a 300mm thick wall between it and us, neighbours might not be best pleased though!

[markocosic]

An accumulator without pump will be near silent.

 

How long do you need the runtime for?

[SimonD]

On 09/09/2023 at 21:34, jayc89 said:

 

My understanding was that's what a Home Booster did; acted as a breaker tank and supplied a cold feed via a pump to both increase pressure and flow, which is where my original question came from. I also thought I'd need a separate break tank if I was to use a standalone accumulator (like the Salamander linked above), like you say. Although the Salamander docs do suggest that, if the tank's empty, it will only supply at a rate of 12l/min (opposed to whatever it boosts to when full), which, I think, would make it compliant with not needing a break tank in front of it?

 

Grundfos sell a number of different 'home boosters' a couple of which have accumulator tanks. Typically the accumulators do act as a break tank from the mains. As @markocosic has suggested, maybe look at a non pumped version. You'll need to decide how long you need the pressure boosted for as that will determine the size of tank.

 

The Grundfos Home Booster tank is pumped and has a usable capacity of 180l @ 0.5 liters/second so about 6minutes worth of boost. Noise level is 65 dB(A)

[joth]

On 10/09/2023 at 10:06, jayc89 said:

 

The Home Booster is similar too, I assumed anything pumped would be. It'd be within a "room" in our loft space so it'd be sitting on top of 400mm of loose cellulose (40kg/m3) then 22mm P5 Caberdek, and I could also get some sort of anti-vibration mat too so I'm hopeful the noise wouldn't be a massive problem. 

 

Alternatively, we have a lean-to on the opposite side of our utility wall so we could fit something in there too, which would have a 300mm thick wall between it and us, neighbours might not be best pleased though!

In a cold loft - you'll need to take some measures to stop it freezing ?  

[jayc89]

16 hours ago, markocosic said:

An accumulator without pump will be near silent.

 

How long do you need the runtime for?

 

We typically shower at similar times, so with an overlap, approx 15 minutes. 

 

2 hours ago, SimonD said:

 

Grundfos sell a number of different 'home boosters' a couple of which have accumulator tanks. Typically the accumulators do act as a break tank from the mains. As @markocosic has suggested, maybe look at a non pumped version. You'll need to decide how long you need the pressure boosted for as that will determine the size of tank.

 

The Grundfos Home Booster tank is pumped and has a usable capacity of 180l @ 0.5 liters/second so about 6minutes worth of boost. Noise level is 65 dB(A)

 

I had only see the ones with a tank, which look to act as a break too. Given our requirements I assumed I'd need a slave tank too, taking the total usable water up to 360l. 

 

28 minutes ago, joth said:

In a cold loft - you'll need to take some measures to stop it freezing ?  

 

That's right. The "room" up there will also be insulated enough to avoid freezing and condensation of the MVHR pipes, which will also be up there. 4x2 studs, filled with wool batts, same for the ceiling. 

[markocosic]

You just need an expansion vessel on the customer side of the stop tap. It isn't a break tank.

 

E.g.

 

https://www.anglianpumping.com/product/accumulator-tanks/450-litre-accumulator-vertical-gws

 

It'll fill to 3 bar when there's no water in use. It'll discharge at 30 litres/minute for a useful length of time when you need the high flow. No pump required.

 

Note the useful capacity of these things is perhaps half the gross capacity.

[jayc89]

How long does an accumulator typically last? Is it worth looking at second hand ones?

[markocosic]

Secondhand tank with new bladder is fine 

[jayc89]

So if using an accumulator would something like this look right?

 

 

I'm assuming the additional DCV before the accumulator would be needed to avoid it boosting the outlets connected to the unbalanced manifold too.

[markocosic]

I'd boost the lot. The toilets etc will reduce incoming mains pressure for a given flow rate anyways; so something off only helps marginally 

[jayc89]

10 minutes ago, markocosic said:

I'd boost the lot. The toilets etc will reduce incoming mains pressure for a given flow rate anyways; so something off only helps marginally 

 

Seems a bit of a waste doesn't it? My thinking was to only use the accumulator for "priority" supplies where I care about the flow; basically showers. Everything else works fines on mains pressure/flow. We'd also want "fresh" drinking water, rather than water stored in the accumulator for any length of time. 

[markocosic]

More check valves is more pressure drop was my thinking 

 

Also the hassle of running (unbalanced) cold water to basins/toilets separately

 

You won't get accumulator water at the kitchen tap if it's teed off before the accumulator unless the mains pressure happens to be high overnight and drop meaningfully during the day

 

[jayc89]

45 minutes ago, markocosic said:

More check valves is more pressure drop was my thinking 

 

Fair point. I think I saw @Nickfromwalesrecommended an oversized DCV and use a reducing ring to go back to the pipe size at either side of it. But given it's already on a 28mm pipe, I think the next size up would be 35mm and they're crazy expensive. Surely the cost outweighs the benefit of saving, what, approx 0.1 bar pressure?

 

45 minutes ago, markocosic said:

You won't get accumulator water at the kitchen tap if it's teed off before the accumulator unless the mains pressure happens to be high overnight and drop meaningfully during the day

 

That's OK, we typically shower in the evenings so want to try keep the accumulator fully charged throughout the day if we can (assuming pressure increases overnight) and mains flow is 12 LPM so, if that's predominantly shared between toilets, washing machine, dish washer and drinking outlets, we can probably manage with that. It's the drop when someone wants a shower that I'm trying to fix. 

[Nickfromwales]

7 hours ago, jayc89 said:

 

Fair point. I think I saw @Nickfromwalesrecommended an oversized DCV and use a reducing ring to go back to the pipe size at either side of it. But given it's already on a 28mm pipe, I think the next size up would be 35mm and they're crazy expensive. Surely the cost outweighs the benefit of saving, what, approx 0.1 bar pressure?

 

 

That's OK, we typically shower in the evenings so want to try keep the accumulator fully charged throughout the day if we can (assuming pressure increases overnight) and mains flow is 12 LPM so, if that's predominantly shared between toilets, washing machine, dish washer and drinking outlets, we can probably manage with that. It's the drop when someone wants a shower that I'm trying to fix. 

You should have all the ‘white goods’ etc straight off the mains, then a NRV and then the accumulator > bathing. The outside taps should be off the mains before it enters the building. 

[jayc89]

2 hours ago, Nickfromwales said:

You should have all the ‘white goods’ etc straight off the mains, then a NRV and then the accumulator > bathing. The outside taps should be off the mains before it enters the building. 

 

Thanks Nick. What about drinking water (i.e. kitchen tap)? Or is that down to personal preference?

[Lofty718]

Have you considered upgrading your incoming water main? (if it's lead)

[Nickfromwales]

39 minutes ago, jayc89 said:

 

Thanks Nick. What about drinking water (i.e. kitchen tap)? Or is that down to personal preference?

Always off the hard mains normally, but down to preference (and understanding why the choice is made) tbh.

[jayc89]

14 minutes ago, Lofty718 said:

Have you considered upgrading your incoming water main? (if it's lead)

 

32mm MDPE now, converted to 28mm copper in the house, followed by a full bore lever, before the UVC control block. 3 bar pressure but flow still sucks, approx 12 LPM. 

[Big Jimbo]

@jayc89 prob a bit silly, but my current crappy bungalow has a 9kw electric shower, lead main 80 years old. Wife always complained that she could not get the shampoo out of her hair. I swapped the shower head for One that we had around, (i assume a shed purchase) It's like a totally different shower. Now my small brain tells me that it is only delivering the same amount of water, but at a higher pressure and is so much better. I assume that the shower head must have much smaller outlet holes?