New radiators - totally baffled!

ThisIsWeird

FreeBear said:

Albermarle said:

A1ps said:

FreeBear said:

A1ps said: Regarding the hot water temp - that is 60 right now and as it stands is scolding hot. I was actually going to lower it to 55, but if that's not a good idea due to risk of Legionnaire's, I'll leave it as it is.

If you have a combi boiler or an unvented hot water tank, you will be perfectly safe dropping the water temperature down to 50°C. Even with a vented system with a header tank up in the loft, the risk of legionella is extremely low - You have a better chance of being hit by a No.13 bus.

Yes, if you have an open header tank where birds can poop in the water, there is an increased risk, but how many domestic properties have such a thing.

Thanks FB. I dont know if this'll make any difference, but I lowered it to 57. Water is still piping hot, but I suspect that's because the last plumber increased the temperature at the MegaFlo. Unfortunately, the megaflo doesn't have markers for temperature, so it's a guessing game as to how hot he's set it to. But I think he did say 65 degrees.

Most boilers only have one flow temperature, for heating and hot water. So if the flow temperature is 57 degrees, it is not physically possible for the hot water to get any hotter than that, regardless of what the megaflow tank thermostat is set at.
If your hot water outlet is not too far from the tank, then it is probably coming out over 50 degrees, which still feels pretty hot to a human hand.

Any boiler that the flow temperature can be controlled via the thermostat/controller can do different flow temperatures for heating & DHW. Some will even have an internal switch connection to alternate between the two. Priority Domestic Hot Water is the label to look for - Some boiler manufacturers will offer a PDHW kit, others just need an appropriate controller and a few modifications to the wiring & (possibly) plumbing.

This blog post, along with the follow ups, gives some thoughts on the subject - https://heatingacademynorthampton.co.uk/s_and_y_plans_should_be_banned/

I think Albe was referring to most currently-installed heat-only and system boilers. Certainly, very few external controllers will have this feature, afaIk. 
With most S and Y plans setups, the boiler just receives a simple 'on/off' signal, and has one output temp control.
Do you know when it became standard or common for boilers to have this PDHW? 

FreeBear

ThisIsWeird said:

FreeBear said:

Albermarle said:

A1ps said:

FreeBear said:

A1ps said: Regarding the hot water temp - that is 60 right now and as it stands is scolding hot. I was actually going to lower it to 55, but if that's not a good idea due to risk of Legionnaire's, I'll leave it as it is.

If you have a combi boiler or an unvented hot water tank, you will be perfectly safe dropping the water temperature down to 50°C. Even with a vented system with a header tank up in the loft, the risk of legionella is extremely low - You have a better chance of being hit by a No.13 bus.

Yes, if you have an open header tank where birds can poop in the water, there is an increased risk, but how many domestic properties have such a thing.

Thanks FB. I dont know if this'll make any difference, but I lowered it to 57. Water is still piping hot, but I suspect that's because the last plumber increased the temperature at the MegaFlo. Unfortunately, the megaflo doesn't have markers for temperature, so it's a guessing game as to how hot he's set it to. But I think he did say 65 degrees.

Most boilers only have one flow temperature, for heating and hot water. So if the flow temperature is 57 degrees, it is not physically possible for the hot water to get any hotter than that, regardless of what the megaflow tank thermostat is set at.
If your hot water outlet is not too far from the tank, then it is probably coming out over 50 degrees, which still feels pretty hot to a human hand.

Any boiler that the flow temperature can be controlled via the thermostat/controller can do different flow temperatures for heating & DHW. Some will even have an internal switch connection to alternate between the two. Priority Domestic Hot Water is the label to look for - Some boiler manufacturers will offer a PDHW kit, others just need an appropriate controller and a few modifications to the wiring & (possibly) plumbing.

This blog post, along with the follow ups, gives some thoughts on the subject - https://heatingacademynorthampton.co.uk/s_and_y_plans_should_be_banned/

I think Albe was referring to most currently-installed heat-only and system boilers. Certainly, very few external controllers will have this feature, afaIk. 
With most S and Y plans setups, the boiler just receives a simple 'on/off' signal, and has one output temp control.
Do you know when it became standard or common for boilers to have this PDHW? 

Any boiler with OpenTherm, EMS, MBUS, etc, can do PDHW, so the capability has been around for quite a while. Certainly, any new system/heat only boiler fitted today will be able to do PDHW.

A1ps

Albermarle said:

A1ps said:

FreeBear said:

A1ps said: Regarding the hot water temp - that is 60 right now and as it stands is scolding hot. I was actually going to lower it to 55, but if that's not a good idea due to risk of Legionnaire's, I'll leave it as it is.

If you have a combi boiler or an unvented hot water tank, you will be perfectly safe dropping the water temperature down to 50°C. Even with a vented system with a header tank up in the loft, the risk of legionella is extremely low - You have a better chance of being hit by a No.13 bus.

Yes, if you have an open header tank where birds can poop in the water, there is an increased risk, but how many domestic properties have such a thing.

Thanks FB. I dont know if this'll make any difference, but I lowered it to 57. Water is still piping hot, but I suspect that's because the last plumber increased the temperature at the MegaFlo. Unfortunately, the megaflo doesn't have markers for temperature, so it's a guessing game as to how hot he's set it to. But I think he did say 65 degrees.

Most boilers only have one flow temperature, for heating and hot water. So if the flow temperature is 57 degrees, it is not physically possible for the hot water to get any hotter than that, regardless of what the megaflow tank thermostat is set at.
If your hot water outlet is not too far from the tank, then it is probably coming out over 50 degrees, which still feels pretty hot to a human hand.

I have 2 settings - 1 for HW (tap symbol) and the other for the rads (rad symbol). 

The hot water problem is that it's set at 2 points - 1 at the megaflow and the other at the boiler. I believe the boiler needs to be set about 5oc lower than the temp at the megaflow. 

I think I'll move the boiler down to 55 today as it really is feeling even hotter now that the weather's improved. Surely that wouldn't make a difference, would it?

ThisIsWeird

A1ps said:

I have 2 settings - 1 for HW (tap symbol) and the other for the rads (rad symbol). 

The hot water problem is that it's set at 2 points - 1 at the megaflow and the other at the boiler. I believe the boiler needs to be set about 5oc lower than the temp at the megaflow. 

I think I'll move the boiler down to 55 today as it really is feeling even hotter now that the weather's improved. Surely that wouldn't make a difference, would it?

I'd have thought that the boiler flow temp would need to be higher than that requested by the Megaflo, or else the Mega would never get up to temp?

I'm really not sure on the best way to sort this, as too low a DHW boiler flow temp would have the Mega taking ages to heat up.

I think I'd try the boiler DHW at, say, 65o, and the Mega to 55o. The Mega will stop calling once it reaches 55o, and up until then it should be returning nicely cool water to the boiler, and it's the return water temp that does the condensing.

But, I don't know.

A1ps

ThisIsWeird said:

FreeBear said:

Albermarle said:

A1ps said:

FreeBear said:

A1ps said: Regarding the hot water temp - that is 60 right now and as it stands is scolding hot. I was actually going to lower it to 55, but if that's not a good idea due to risk of Legionnaire's, I'll leave it as it is.

If you have a combi boiler or an unvented hot water tank, you will be perfectly safe dropping the water temperature down to 50°C. Even with a vented system with a header tank up in the loft, the risk of legionella is extremely low - You have a better chance of being hit by a No.13 bus.

Yes, if you have an open header tank where birds can poop in the water, there is an increased risk, but how many domestic properties have such a thing.

Thanks FB. I dont know if this'll make any difference, but I lowered it to 57. Water is still piping hot, but I suspect that's because the last plumber increased the temperature at the MegaFlo. Unfortunately, the megaflo doesn't have markers for temperature, so it's a guessing game as to how hot he's set it to. But I think he did say 65 degrees.

Most boilers only have one flow temperature, for heating and hot water. So if the flow temperature is 57 degrees, it is not physically possible for the hot water to get any hotter than that, regardless of what the megaflow tank thermostat is set at.
If your hot water outlet is not too far from the tank, then it is probably coming out over 50 degrees, which still feels pretty hot to a human hand.

Any boiler that the flow temperature can be controlled via the thermostat/controller can do different flow temperatures for heating & DHW. Some will even have an internal switch connection to alternate between the two. Priority Domestic Hot Water is the label to look for - Some boiler manufacturers will offer a PDHW kit, others just need an appropriate controller and a few modifications to the wiring & (possibly) plumbing.

This blog post, along with the follow ups, gives some thoughts on the subject - https://heatingacademynorthampton.co.uk/s_and_y_plans_should_be_banned/

I think Albe was referring to most currently-installed heat-only and system boilers. Certainly, very few external controllers will have this feature, afaIk. 
With most S and Y plans setups, the boiler just receives a simple 'on/off' signal, and has one output temp control.
Do you know when it became standard or common for boilers to have this PDHW? 

I'm quite certain I have an S plan setup as I have UFH on the ground floor. I remember the plumber who installed it insisted on this setup being the best option. 

A1ps

FreeBear said:

Fitted T22 in the lounge & dining rooms, and they stick out a lot more than the T21 radiators. Personally, I prefer the slimmer profile of the T21..

Oh, and City Plumbing were very competitive on prices - The Stelrad Halcyon was marginally more expensive than Flomasta from Screwfix, but they did free delivery. I see the Stelrad prices have increased since last year - Might be worth paying a personal to one of their trade counters and haggle over the price.

I just looked at City Plumbing and ScrewFix and like for like their prices are a lot more than Stelrad.

For a 600 x 1100:

City Plumbing - £201.59

ScrewFix - £155.99

Stelrad - £117.04

I also did the measurements finally and have decided the following based on space, what's needed by way of BTU (all of them have more than what's needed), and from all the great advice and help you all have given.

My room - 600 x 1100. 1200 would've been great but I would've been encroaching a little too close to the bedside cabinet.

Kids - 600 x 1000. They have a small room and any more than this will be overkill.

Mum's - 600 x 800. Same as the kids, any bigger would be overkill. 

Loft - 600 x 1100 either side of the room. If I split the room in 2, each side would be the size of my room, so went with the same size as my room. 

Hall - 600 x 700. Didn't really need to go bigger, but went with your advice and increased the size by 100.

A1ps

ThisIsWeird said:

A1ps said:

I have 2 settings - 1 for HW (tap symbol) and the other for the rads (rad symbol). 

The hot water problem is that it's set at 2 points - 1 at the megaflow and the other at the boiler. I believe the boiler needs to be set about 5oc lower than the temp at the megaflow. 

I think I'll move the boiler down to 55 today as it really is feeling even hotter now that the weather's improved. Surely that wouldn't make a difference, would it?

I'd have thought that the boiler flow temp would need to be higher than that requested by the Megaflo, or else the Mega would never get up to temp?

I'm really not sure on the best way to sort this, as too low a DHW boiler flow temp would have the Mega taking ages to heat up.

I think I'd try the boiler DHW at, say, 65o, and the Mega to 55o. The Mega will stop calling once it reaches 55o, and up until then it should be returning nicely cool water to the boiler, and it's the return water temp that does the condensing.

But, I don't know.

Ahh! You're right. That makes a lot more sense. I know how to get to the controls on the megaflow setting, I just can't guesstimate how much to turn it down by as stupidly they didn't put any markers on the temp setting! But will try moving it down a touch later this afternoon.

There's a boiler control and element control. It would be the bolder control I'd need to adjust, right?

This is the setting. Where the yellow marker is, is the current setting.

FreeBear

A1ps said:

FreeBear said:

Fitted T22 in the lounge & dining rooms, and they stick out a lot more than the T21 radiators. Personally, I prefer the slimmer profile of the T21..

Oh, and City Plumbing were very competitive on prices - The Stelrad Halcyon was marginally more expensive than Flomasta from Screwfix, but they did free delivery. I see the Stelrad prices have increased since last year - Might be worth paying a personal to one of their trade counters and haggle over the price.

I just looked at City Plumbing and ScrewFix and like for like their prices are a lot more than Stelrad.

Don't forget, City Plumbing is primarily a trade supplier, and the web prices are not always the same as the over-counter price. Having said that, Stelrad prices have gone up by quite a bit, so I was probably lucky to get mine when I did.

A1ps

Guys, thank you so much for your help. after weeks of stressing, measuring, calculating, stressing, remeasuring, calculating, stressing, I've finally ordered the 6 rads.

@FreeBear I spoke with CityPlumbing but they couldn't come close to the price even at trade. So in the end I went direct with Stelrad. 

After some last minute measuring, calculating and stressing, I played it safe with the space restrictions and went with:

My bedroom, kids, and loft - 600 x 1000

Mum's and hallway - 600 x 700.

Each room is 100 larger than the existing ones, and well and truly above the BTU and Watts needed, but as you guys thankfully recommended, at least I can turn them down if needed.

If any of you are local to North London, I owe you a drink of what every is your preference 

FreeBear

A1ps said: If any of you are local to North London, I owe you a drink of what every is your preference 

That would be a Quinta do Noval Nacional, 1963 for me (got expensive tastes )