Best spec for high pressure hot water to multiple outlets?

[Onoff]

23 minutes ago, PeterW said:

So when the hot water comes on, does the 3 way valve spin over to open or does it just heat the water ..??

 

With a HRC and small cylinder you may want to add a midday time slot to the programme. Would also say that if it can heat a tank in 30 mins then most likely it’s sub 150 litres. 

 

Sorry I really don't know. It's a Honeywell V4073A1088 mid position valve if that helps?

 

I'll measure the insulation and see if I can make a more accurate stab at the tank capacity.

 

Thanks.

[PeterW]

Get someone to boost the hot water whilst you’ve got a hand on the valve. Soon see if the pipework gets hot without the motor triggering. 

[hendriQ]

On 16/01/2021 at 18:41, Adsibob said:

One exception was an impressive Austrian made Ochsner air source heat pump which was some sort of table system that also drew heat from rainwater as well as air. It was quiet enough and possible to install in the back garden where it wouldn't need planning permission. But the supply and installation was coming to around £20k and it would have also made our utility room quite a lot smaller because of the rather large sized compressor. They also didn't have as good warranties as the Veismman and the annual service was more expensive too. These prices are just not really realistic and it's frustrating the government has not done more to incentivise advances in this type of technology or make it easier to drill bores in your front drive/yard.

Did you end up finding a air source heat pump to suit your requirements?

 

Anyone else have experience with the Ochsner?

[Adsibob]

38 minutes ago, hendriQ said:

Did you end up finding a air source heat pump to suit your requirements?

Alas, no. For what I wanted it was either £3k for a gas system, or £17k for a green system. I just can’t make that fit my increasingly strained budget. It’s a shame because I just don’t think the government’s announcement yesterday about hitting C02 abatement targets by 2035 is realistic without introducing a hydrocarbon tax, and bringing in tax incentives for green energy. I just fear it’s too late for my project. Unless I install a gas boiler now and accept that I will have to change to something greener when it packs up in 10 to 15 years time, having damaged the planet in the interim.

[Dan F]

15 minutes ago, Adsibob said:

Alas, no. For what I wanted it was either £3k for a gas system, or £17k for a green system. I just can’t make that fit my increasingly strained budget. It’s a shame because I just don’t think the government’s announcement yesterday about hitting C02 abatement targets by 2035 is realistic without introducing a hydrocarbon tax, and bringing in tax incentives for green energy. I just fear it’s too late for my project. Unless I install a gas boiler now and accept that I will have to change to something greener when it packs up in 10 to 15 years time, having damaged the planet in the interim.

 

ASHP is £3,500-4,000 max, any idea what the other £13k is for?   Or is 17k based on Ochsner ASHP?

[Adsibob]

1 hour ago, Dan F said:

 

ASHP is £3,500-4,000 max, any idea what the other £13k is for?   Or is 17k based on Ochsner ASHP?

Yes, an Ochsner. Includes installation of the unit externally and compressor internally. Only unit I know of to operate very quietly, extremely efficiently and have a build quality that means it will last and last.

I'm very much open to cheaper alternatives, but I don't want to install something that I'm going to hear, whether in my house or in my garden.

[volcane]

I considered an Ochsner split system but the short warranty (2 years) for something that's supposed to be better built along with high service charges put me off

[Adsibob]

2 minutes ago, volcane said:

I considered an Ochsner split system but the short warranty (2 years) for something that's supposed to be better built along with high service charges put me off

Thanks @volcane. Yeah, to be honest that put me off as well, particularly most decent gas boilers come with a 7 or in some cases a 10 year warranty now. What did you go for in the end?

[Dan F]

36 minutes ago, Adsibob said:

Yes, an Ochsner. Includes installation of the unit externally and compressor internally. Only unit I know of to operate very quietly, extremely efficiently and have a build quality that means it will last and last.

I'm very much open to cheaper alternatives, but I don't want to install something that I'm going to hear, whether in my house or in my garden.

 

Does look to be very quiet (AIR HAWK 208 at least), but:

- Doesn't seem to be any more effieicnt than other newer heat pumps available.

- I won't be putting compressor in the house, however quiet it is: i) wouldn't want to loose space ii) prefer any small amount of noise to be outside and not inside.

- What is the dB rating of the gas system you are looking at?  The boilers i've seen are 55/60dB (sound power). not much different to most ASHP's I don't think which seem to be around 55dB.

 

(remember 55dB sound power at 5m, assuming one reflective surface and no barriers, is 34dB sound pressure which is what you perceive)

Edited April 20, 2021 by Dan F

[Adsibob]

53 minutes ago, Dan F said:

What is the dB rating of the gas system you are looking at?  The boilers i've seen are 55/60dB (sound power). not much different to most ASHP's I don't think which seem to be around 55dB.

 

(remember 55dB sound power at 5m, assuming one reflective surface and no barriers, is 34dB sound pressure which is what you perceive)

I am looking at the Veissman Vitodens-200W, which is described as “The boiler's special design ensures the very low operating noise of 39 dB(A) maximum (26 kW)”.

[Dan F]

11 hours ago, Adsibob said:

I am looking at the Veissman Vitodens-200W, which is described as “The boiler's special design ensures the very low operating noise of 39 dB(A) maximum (26 kW)”.

 

You do need to be very careful with dB ratings because "sound power" on full power is very different to "sound pressure" at 1m or more, or running in a low-noise mode.   Marketing materials , for obvious reasons, often use the later.  For example, the ASHP we are using has 55dB sound power running at A7/W55.   (This equates to 47 dB sound pressure at 1m and  37 dB sound pressure at 3m).  They also specify 46dB sound power running A7/W35 is quiet mode.  (This equates to 38 dB sound pressure at 1m and  29 dB sound pressure at 3m)

 

IF you look at the Veissman Vitodens-200W technical data, the actual "sound power" values are 46dB for 26kW version and 48dB for thr 32kW model.  At partial load it's 36dB though, so about the same as a fridge.

 

Only you know how much noise is an issue, a lot of this depends on how far away from your garden and windows you may open you could put one. In our case it's 4m to nearest window and 10m from garden, so we won't hear a thing from the garden and at the window sound pressure will be 30dB max and so not noticeable above background noise.

 

Edited April 21, 2021 by Dan F

[Adsibob]

On 17/01/2021 at 00:06, PeterW said:

As I said, min 400 litres in a house that size as for the £75 difference it’s just not worth the hassle. 

Can anyone recommend a 400L horizontal unvented cylinder? I think the largest horizontal one Telford does is 300L.

[PeterW]

46 minutes ago, Adsibob said:

Can anyone recommend a 400L horizontal unvented cylinder? I think the largest horizontal one Telford does is 300L.

Speak to Trevor at Cylinders2Go - Telford do all their cylinders in every size to 500 litre. 

[Adsibob]

33 minutes ago, PeterW said:

Speak to Trevor at Cylinders2Go - Telford do all their cylinders in every size to 500 litre. 

That's helpful thanks. I've actually just found a 400L horizontal one. But what I'm confused about is that the flow rate is only 55L/m. That's less than half the flow rate adverstised with a Megaflo from Heatrae Sadia which apparently can do 130L/m. My understanding is that the main difference between the two technologies is that with an indirect unvented system, the Telford Tempest would need a separate expansion vessel whereas the Megaflo has some sort of air gap built in, so more efficient in its use of space and easier to install. But why would the flow rates be so different? Or is this all academic if the flow rate I'm getting from the street is about 20L/m to 25L/m with pressure of 3 bar?

[PeterW]

Megaflo is old technology. What’s the issue with having an external expansion like every other UVC..?

 

And you cannot use 55L/min anyway - a cold mains will struggle to do that so why get obsessed over how fast a tank will empty ..??

[Adsibob]

1 hour ago, PeterW said:

Megaflo is old technology. What’s the issue with having an external expansion like every other UVC..?

 

And you cannot use 55L/min anyway - a cold mains will struggle to do that so why get obsessed over how fast a tank will empty ..??

I think I was just trying to understand the relevance of the flow rate of the tank. Is what you are saying that if my main water supply only gives me 20 to 25 L/m, i won’t see a difference between a 55L/m tank or a 130L/m? In both cases I will just get 20 to 25 L/m? But what if I have three outlets open at the same time? Won’t the 55L/m limit on the Telford Tempest kick in then, and limit my flow per outlet to 18.33L/m ?

[PeterW]

No - difference is 28mm vs 22mm connection and tbh you’ll not notice as taps are your limiting factor

[Adsibob]

43 minutes ago, PeterW said:

taps are your limiting factor

I’ve purchased a bath filler with a 33L/min flow rate (at 3bar) and thermostatic valves for the showers that can do 30L/min (also at 3 bar). Guest WC basin mixer and kitchen tap are both rated at 24L/min each. So as long as i fit wide enough pipes, I’m not sure the limiting factor will be the taps?

[PeterW]

Have you ever seen 30 litres a minute ..???

 

For comparison that is a 5 litre container every 10 seconds, a 2 litre pop bottle in 4 seconds ..?? It is fire hose type flows through showers ...

 

None of your taps meet water regs to meet the flow requirements - I would have restrictors on basins to 6l/min, kitchen at max 9l/min as otherwise you’re going to have water everywhere. 
 

You really don’t need flow rates much about 9-12l/min on a shower, bath is probably the only one where you want a slightly higher flow. 

[Adsibob]

1 hour ago, PeterW said:

Have you ever seen 30 litres a minute ..???

 

For comparison that is a 5 litre container every 10 seconds, a 2 litre pop bottle in 4 seconds ..?? It is fire hose type flows through showers ...

 

None of your taps meet water regs to meet the flow requirements - I would have restrictors on basins to 6l/min, kitchen at max 9l/min as otherwise you’re going to have water everywhere. 
 

You really don’t need flow rates much about 9-12l/min on a shower, bath is probably the only one where you want a slightly higher flow. 

Thanks, that's helpful.  The taps are supplied with restrictors but these can be removed to increase the flow rate. The only area where I would actually want to do that and get as much flow as possible is the bath filler, as it's a HUGE bath and possibly the rain shower. I'm assuming I will lose some pressure anyway from the 2.8 to 3.2 bars coming in to the property at ground floor and the location of the UHWC which is about 6.5m or 7m above that on the second floor, so in actual fact I won't get the flow rates advertised for these taps/showers at 3 bar, but slightly less. Is the calculation simply 0.65 to 0.7 bar less to account for the 6.5m to 7m height travel?  

[Adsibob]

9 minutes ago, Adsibob said:

I would have restrictors on basins to 6l/min, kitchen at max 9l/min as otherwise you’re going to have water everywhere. 

Is it possible to restrict the flow using narrower pipes. I'm having a secondary loop for the hot water to the bath and basins (but not the showers). For for the basins could I just use a narrow pipe to join the hot water secondary loop to the basin, and supply cold water with narrower pipes as well?

[PeterW]

10mm to basins, 10mm to WCs, 15mm to showers and 22mm to the swimming pool by the sounds of it. 

[Adsibob]

1 hour ago, PeterW said:

10mm to basins, 10mm to WCs, 15mm to showers and 22mm to the swimming pool by the sounds of it. 

This really is very helpful thank you. I assume I would make the secondary loop itself 22mm as well?

[PeterW]

No. Secondary only 22mm to the supply points such as the tap tees then 10mm back from the furthest point. 

[hendriQ]

On 24/05/2021 at 16:08, PeterW said:

10mm to basins, 10mm to WCs, 15mm to showers and 22mm to the swimming pool by the sounds of it. 

Is that the same recommendation regardless of whether one is using plastic or copper pipes?