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New radiators - totally baffled!

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  • A1ps
    A1ps Posts: 89 Forumite
    Seventh Anniversary 10 Posts Name Dropper
    A1ps said:
    A1ps said:
    I just checked my flow temperature on the boiler - it is in fact 65 degrees NOT 55 as I guessed before.

    @ThisIsWeird thanks for the link. I'm going to measure the window width tonight to make sure this size fits the width. If not, will look at ones that do fit. 

    Are there any negatives for going for FloMasta over the Stelrad? Price isn't an issue as I want to make sure I get it right first time round, regardless of cost.
    A 65oC flow temp makes sense, as a 55o temp runs the risk of not heating your hot water cylinder adequately to guard against Legionnaire's.
    Re making the rad suit the window - that was partly said in jest, as the most crude way to determine the 'correct' rad size. It was based on some info, tho', and the assumption that a 1600mm rad, at 2.1kW, should be ok for that room. FreeBear has pointed out, tho', that a reduced flow temp will seriously affect the rad's output, so even 1600mm might not be large enough. And, yes, I was taken aback by the jump in cost. But, if you want to heat a room properly, run it on cooler water, then make sure the rad is 'big enough'.
    In short, you cannot fit a rad that's 'too' big.
    A thought - try a look on Facebook Marketplace. I've just tried that over here, and there's a good selection of second hand rads, in very good condition, for £5 a pop. There's even an ad for 5 brand new rads for £150 - 2 are 1200mm.
    What I'm basically saying is, absolutely do the 'calcs' so's you have a baseline to compare by, but - more than this - judge what the new size should be by the performance of the existing. That 900mm one in your bedroom, for example, by your own account is just ain't cutting the mustard, so you will need an increase based on just how little mustard-cutting it is achieving. If it's 'almost' good enough, then perhaps three or four hundred more watts will be fine? If it's 'well chill', then you'll likely need the best part of an extra kW. And then add some 'over-sizing' if you can, to allow you to turn the boiler flow down. What size do you end up with? Does it seem ok? Worth edging up another size unit? Adding extra fins?!
    It's a very rough science - unless you have a modern home, insulated to a high degree. Then you can choose rads with some precision.

    I feel proper silly right now as I actually went and done the measurements and was going to come back and say just how super big and impractical that size would be... and how silly it would look  :D I'm laughing as I type this :D 

    The max I could go is 1100 as any more than that would encroach on the area by the bedside cabinet.

    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.

    The radiator temp is 65 at 2.7 bar.


    I was only half joking, even less.
    A 1100mm rad ain't much more powerful than what you currently have, and certainly won't be effective if you do turn down the boiler flow temp.
    I'd personally still oversize.
    60o for your DHW is perfectly fine. You'd prob get away with it less, as Leg would struggle to survive in that, but - again personally - I'd leave it at 60, or close to.
    Your boiler pressure is 2.7bar? That has no bearing on the temp, but is actually uncomfortably high for the system - it'll activate a safety valve at 3bar.
    What pressure is it at when cold?
    Thanks TIW. I'll need to remeasure all the spaces where the rads are going. My room and the loft are the only 2 rooms where I can get away with a fair bit bigger. The kids and mum's room will struggle. Kids can possibly go from 900 to 1000, but def no more. Mum's no way. And, TBH, that room is the warmest in the house so doesn't really need a bigger rad.

    Regarding the 2.7 bar. I've read how to lower it, but with my lack of skills in this area, I'll leave it for when the plumber arrives? I'll check the reading when everything has cooled down. I've just read I should get it down to 2.
  • A1ps
    A1ps Posts: 89 Forumite
    Seventh Anniversary 10 Posts Name Dropper
    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.
  • A1ps
    A1ps Posts: 89 Forumite
    Seventh Anniversary 10 Posts Name Dropper
    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.

    Plus if it is a family home with a regular/daily usage of hot water, the very minimal risk becomes even more minute.
    Oh believe you me, the hot water gets plenty of use.... I live in a house with 4 women  :s
  • A1ps
    A1ps Posts: 89 Forumite
    Seventh Anniversary 10 Posts Name Dropper
    I'm going to do all the measurements tomorrow and order the rads. 

    Hoping to squeeze in 1200 in my room and loft.

    1000 in the kids room. 

    Hopefully squeeze in 700 in mum's. But she doesn't really need any bigger. But as the saying goes better to have a gun and not need it, than to need a gun and not have it :D 

    And the hallway I'm going to stick with the 600 as it only ever comes on when it's super cold. It's the warmest place in the house. 

    Wish me luck  :#
  • A1ps
    A1ps Posts: 89 Forumite
    Seventh Anniversary 10 Posts Name Dropper
    So, now that I'm definitely going bigger, should I also go for 2.2? Or stick 2.1?

    Would the 2.2 rads be deeper than 2.1?
  • BarelySentientAI
    BarelySentientAI Posts: 2,448 Forumite
    1,000 Posts Name Dropper
    A1ps said:
    So, now that I'm definitely going bigger, should I also go for 2.2? Or stick 2.1?

    Would the 2.2 rads be deeper than 2.1?

              
  • A1ps
    A1ps Posts: 89 Forumite
    Seventh Anniversary 10 Posts Name Dropper
    The tape measure's gonna get a lotta use tomorrow  :D But going by those pics, the rads will most likely be 21
  • FreeBear
    FreeBear Posts: 16,408 Forumite
    Ninth Anniversary 10,000 Posts Name Dropper Photogenic
    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.
    Her courage will change the world.

    Treasure the moments that you have. Savour them for as long as you can for they will never come back again.
  • Albermarle
    Albermarle Posts: 24,468 Forumite
    10,000 Posts Sixth Anniversary Name Dropper
    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.
  • FreeBear
    FreeBear Posts: 16,408 Forumite
    Ninth Anniversary 10,000 Posts Name Dropper Photogenic
    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/


    Her courage will change the world.

    Treasure the moments that you have. Savour them for as long as you can for they will never come back again.
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