You could also get yourselves a 4.8 v8 Chevy ( proven, tried and tested method that works) to carry your tools around in, but you wouldn't !.....? :hand:
Welcome to the forum. Although you can post in any forum, the USA forum is here in case of local regs or laws
- Thread starter mutley racers
- Start date
You could also get yourselves a 4.8 v8 Chevy ( proven, tried and tested method that works) to carry your tools around in, but you wouldn't !.....? :hand:
Sure thing pipe monkey 🙂
Seriously though sometimes you have to accept that things change, nothing about what you were doing before being wrong, just a different way otherwise we would still be burning coal.
Last edited:
Double glazing, loft insulation, fitted carpets, less ventilation but more importantly an accurate method for figuring heat loss using a logical process rather than a formula written on the back of a *** packet in 1950.
Bottom line is each to their own, I don't care how big a radiator you specify as it won't be going in my house.
I'm surprised that some of the things people are advised against on here could be seen as trivial (whether or not to put jointing compound or PTFE on an olive) yet sizing a radiator and ultimately a full heating system in the correct way is frowned upon.
Bottom line is each to their own, I don't care how big a radiator you specify as it won't be going in my house.
I'm surprised that some of the things people are advised against on here could be seen as trivial (whether or not to put jointing compound or PTFE on an olive) yet sizing a radiator and ultimately a full heating system in the correct way is frowned upon.
I'm not frowning upon anything and if I had to sit down and design a heating system for scratch for money then calculations it would be. All I'm saying is that I can go and do a quck calculation (in my head) and define the rad or rads there and then. All based on experience and what I see.
I used to think this was magical because my boss used to do this when I was an apprentice. He would have me calculating the U value of all the surfaces using r values and define the heat loss down to the nearest btu. My calcs and his estimate would be within 50btu's either way.
All I'm saying is that it works for me and rarely get it wrong.
But to be called unprofessional because that's the way I do it is not on.
I used to think this was magical because my boss used to do this when I was an apprentice. He would have me calculating the U value of all the surfaces using r values and define the heat loss down to the nearest btu. My calcs and his estimate would be within 50btu's either way.
All I'm saying is that it works for me and rarely get it wrong.
But to be called unprofessional because that's the way I do it is not on.
Last edited:
With all due respect simonG I did specifically say that no offence was intended. I'm not doubting or questioning your experience or ability in the trade, I've no right too, I don't know you and I've no interest to do so either. (doubt you)
The example above about being 50 btu's out cannot possibly be correct seeing as a simple change in wall construction from solid to insulated cavity could cause a greater difference and the ft2x5 rule of thumb can't allow for construction material.
Its pretty obvious not just from your replies but from the general response that the method me and Chris Watkins are familiar with isn't common practice amongst the majority on here and most definitely not with the majority of engineers I have met or worked with over the years in my area. That's not surprising as most systems aren't installed with economy in mind. If it gets hot enough it works tends to be the general approach, and it will because the rule of thumb and mears calculator All oversize by quite a way.
Its almost like saying we should put a 35mm gas supply in for every new boiler because it will always work.
All I will say is that times are changing and new technologies and restraints call for more accurate methods in sizing emitters, heat pumps being a prime example. If required there are spreadsheets available for free that make the whole process take about 2 mins per room, a little more if the construction material is non standard.
I'm happy to agree to disagree, and if you genuinely thought my comments were out of order, I apologise as it was intended to be a bit tongue in cheek and certainly not meant to cause offence.
The example above about being 50 btu's out cannot possibly be correct seeing as a simple change in wall construction from solid to insulated cavity could cause a greater difference and the ft2x5 rule of thumb can't allow for construction material.
Its pretty obvious not just from your replies but from the general response that the method me and Chris Watkins are familiar with isn't common practice amongst the majority on here and most definitely not with the majority of engineers I have met or worked with over the years in my area. That's not surprising as most systems aren't installed with economy in mind. If it gets hot enough it works tends to be the general approach, and it will because the rule of thumb and mears calculator All oversize by quite a way.
Its almost like saying we should put a 35mm gas supply in for every new boiler because it will always work.
All I will say is that times are changing and new technologies and restraints call for more accurate methods in sizing emitters, heat pumps being a prime example. If required there are spreadsheets available for free that make the whole process take about 2 mins per room, a little more if the construction material is non standard.
I'm happy to agree to disagree, and if you genuinely thought my comments were out of order, I apologise as it was intended to be a bit tongue in cheek and certainly not meant to cause offence.
Last edited:
How do you know that you don't get it wrong then Simon ? if you don't do a calc involving measuring the room & windows, checking the construction of the building etc how would you know? You, & I agree most other plumbers do guess-emate to size a rad & that includes no corrections to the rad table outputs which are based on a temp difference of 50deg C.
Do you know what I believe Sambotc, I think the hostile reaction we receive ever time this gets brought up (not just on this forum) has more to do with the fact that a lot of plumbers & so call heating engineers do not know how to do this, have no interest in finding out how it is done (even when it is reasonable easy & won't cost them either), they just keep on telling anybody who will listen that they have the 'power' to predict what the heat loss & rad size will be, based upon years of experience dating back to when BTU's where used & their plumber handed on this sacred knowledge. Even though as you say time s have moved on, designs, boilers, heat emitters, insulation etc etc have all moved on !!!!!!!!
It will filter through I think in the next few years as the courses start to include it. As i said above ive no interest if people don't want to know about the changes. In fact I see it as a bonus if I have to quote against a company who pulls numbers out of a hat or if I can sit down and work out the specific requirement on site in minutes and explain the process to the client.
M
Mike Jackson
When I quote a job I always specify the room temperatures that I've allowed but not the rad sizes. I tell the customer that they can have a copy of the calculations including the rad sizes when the job is accepted. If I'm in a rush when doing the quote I can guesstimate the rad sizes needed and do the proper calcs if i get the job. I normally find my guesstimate is larger than the required size.
ive always been a 5 per sqft man and also own a mears wheel for larger than the normal 3 bed house
its all very well having the wonderfull program for calcs if you are on new build work where a u value of each surface is probably an email to the desinger away
how do you work out the u value of a retro fit into a single flat in a block of flats built by persons unknown which is clad in some sort of finish you cant id ?where you dont know if the flat above and below may be heated or not and theres no access to loft space to check insulation levels ?
its all very well having the wonderfull program for calcs if you are on new build work where a u value of each surface is probably an email to the desinger away
how do you work out the u value of a retro fit into a single flat in a block of flats built by persons unknown which is clad in some sort of finish you cant id ?where you dont know if the flat above and below may be heated or not and theres no access to loft space to check insulation levels ?
Simples, you do your best with would you can see but of the other 90% of the time you don't guess.
Now that's standard tender / quoting practice, Mike & I totally agree. No point in wasting time working it all out if no job at the end & why give info away as to what you are going to fit (mainly cos it will be a lot smaller that the others) but when it comes to selecting one well then sizing is a must.
You hadn't posted for a while, didn't know that you had decided the tread should be shut down! Who's slinging mud ? Not me.
PS. If anybody whats any help or advice in doing heatloss or rad sizing correctly, just post in the arms or mail me.
Official Sponsors of Plumbers Talk
Similar plumbing topics
- Question
We recommend City Plumbing Supplies, BES, and Plumbing Superstore for all plumbing supplies.
