Boiler efficiency

Nic

Hi all, sorry for the long message but please bear with. We have a warmflow oil combi boiler. 12 rads. We use a LOT of oil but struggle to keep the house warm. Rarely does it get above 20oC with heating on. One radiator downstairs doesn’t work at all, I’ve taken off, cleaned, added inhibitor and cleaner and it still doesn’t work. My request for help is, how could I make my boiler more efficient and heat the house better and what could be wrong with the 1 radiator. Sorry if there’s loads of options but happy to answer any questions. Thank you

Jamie Hall

Well... where to begin. The first question, of course, is... is the boiler really big enough for the house? To find that out you have to determine the heat loss of the structure (you can't guess or estimate on structure size). There are a number of handy, homeowner usable, calculators available, such as this one: https://www.slantfin.com/slantfin-heat-loss-calculator/

You can get room by room values from that, and add them up and compare them to the output of the boiler, which will be on the nameplate for the boiler.

This isn't a matter of efficiency -- it's purely a matter of heat input vs. heat loss.

Then... assuming that the boiler really is big enough, the question becomes can and does the boiler circulate the water properly to the radiation, and is it set to produce hot enough water? There are so many possibilities there for things to be amiss that without more information it would be imprudent to venture any guesses.

The one radiator that doesn't work at all, though. Are you sure that any control valves on it -- or the lines leading to it -- are open? It's happened. Also, is there any way to bleed air out of it? It may simply be air bound.

pecmsg

The greatest efficacy you can get is Tightening the envelop, that in turn allows a smaller boiler and less fuel burned!
As @Jamie Hall said do a Heat Load / Loss calculation as the structure is now then another with new windows, doors, and improved insulation and Air Sealing.

Steamhead

Looked up Warmflow- is this in the U.K.?

BDR529

90% boiler in a 58% house.. Effcy' is such a loaded term.

Nic

Thank you. I’ll try that advice. The radiator concerned doesn’t have any air in it when bled, but unsure whether to check the valves actually work? I know there’s possibly a lot of things it could be but a basic idea of what to check would be appreciated 

Bronxtech

Pictures of the Radiator and piping/ valves on it would be helpful.
Is this the highest rad in the house/top floor?
John 

PC7060

Nic said:

Thank you. I’ll try that advice. The radiator concerned doesn’t have any air in it when bled, but unsure whether to check the valves actually work? I know there’s possibly a lot of things it could be but a basic idea of what to check would be appreciated 

Is the radiator a new problem? I recently worked an issue with a radiator in a home that suddenly stopped working. I checked flow, nothing. Followed the line back towards boiler and found a closed valve. Opened valve and bingo. Maybe some though they where shutting off outside water?

Anyway, if the pipe are accessible, follow them back towards to boiler to see if the pipe ever warms up. May have a bad valve (zone or otherwise).

RE overall house comfort, best thing to do is look for air leaks or drafty areas you can plug or seal. It's a game of inches (cm?) but every little bit helps. Please provide more information on home construction and overall condition. Is the house masonry, wood frame, insulated, etc. ?

Nic

Thank you. No the radiators been a problem for as long as I can remember but the pipes go into the walls so I’m not sure how to follow back to boiler. The house is brick built, circa 1920 with no cavity, insulation only in the roof space. The radiators tend not to give off much heat and I’m not sure how to find out the btu of the radiator or whether they’re adequate for the space. Also, I’ve read somewhere that the “pump” on the boiler shouldn’t be hot but when I touch it it’s boiling. Could this be an issue? If so how do I check this. Really appreciate your time and expertise 

Nic

Please see attached a couple of photos of the pipes and rad. 

PC7060

Re the cold radiator, wonder if that TRV is bad? I'd take the control head off and press on the plunger a few time to see if its stuck closed. Not sure how you else would check other than loosening the lower nut to see if you get warm/hot water flow. Not a pretty way to test because you'd need to run a fair bit out and it's tricky to catch the water in a bin when that close to floor and wall.

That's a nice sized panel radiator and will be very good to get it back online.

Masonry house are tough to retrofit for insulation without loosing some interior space.

PC7060

More questions: You mentioned the circulator is hot, it that the pump/pipes or the motor? What the temperature of the water leaving the boiler?

Wonder if you have more that one TRV giving you trouble and the circulator is fighting the back pressure

Nic

Thankyou both. The pumps hot to touch and the pipes (I assumed because they were carrying the hot water?) sorry, I’m not sure how to check the temp leaving the boiler. How would I check the TRV’s? 

Thanks for all your help. It would be good to get the radiator working again

PC7060

@Nic - “ How would I check the TRV’s” unscrew the silver ring and remove the control head of the TRV.  Don’t worry, it won’t cause water to come out. You should see a metal rod inside the TRV body,  push it up and down a few time to see if it moves, it may be stuck closed.  The rods are usually a bit stiff (and pokey), may help to put a coin on top.  

Re the temperature, any decent coking thermometer typically works.  I use my wife’s digital thermometer, just like the ones on the British baking show. Just put the tip on the pipe and you’ll get pretty accurate the reading. 

Nic

Hi, I’ve taken the top off the TRV and tried to push the pin. It moves but literally a couple of mm and no more. It’s not stuck down to the bottom but the trv only pushes it down a couple of min anyway? Should it go right down to the bottom, if so how do I release it? Thank you 

PC7060

I have Honeywell TRV which move maybe 1/4”.  Your may be stuck in down position.  Do you have pliers that you can use to pull gently up? May take a little force but not a lot.  Just trying to break the seal loose from seat. 

Nic

I took the top off, the pin was out about 1cm. It would only move up and down about 2mm. However, now, the radiators hot? Ive not done anything so I’m at a loss. Thank you so much for your help if you could shed some light on it that’s be great 

PC7060

Radiator is hot now? Cool! I mean nice!!!
  
Sounds like the TRV seal is bad and sticking to valve seat. With that type it easier to replace entire unit.  You’ll have to drain down system to below that rad since there’s no shutoff for the rad. 

What’s the part number cast into side of the TRV?

JUGHNE

Could it be that some or all of the TRVs are sticking almost closed?
Might explain the very hot pump might be close to "dead heading".

IIWM, I would remove all the TRV heads, exercise the pins and see if things change. Leave the heads off for a day or so.....hopefully enjoy the heat.

You may have been sending a lot of heat up the chimney that lack of water flow may have not picked up enough BTUs.

Nic

DN 15? Does that sound right? 

So would you say to change it? And wiggle the other pins in the radiators? 

I’m so grateful, thanks for your help 

PC7060

@JUGHNE - exactly what I was thinking.  All of the valves may be end of life and causing rads to shutdown early.   Also why I was curious about pump motor temp. 

@nic - search on “dn15 trv angle”; I see a few variants but my search is US based and won’t see options in your market. 

And yes, I’d give all the pins a bit of exercise. Gently though.  

EdTheHeaterMan

By removing the actuator the valve should be completely open. If the pin that closes the valve is only 1 MM out of the valve body, then the valve is partially stuck. That valve is spring-activated open. (failure open) The actuator then closes the valve if the room is heated sufficiently. By getting some heat into the pipes and fittings the actuator may be easier to exercise. (move the pin in and out). This may get more movement in the valve and open it more.

There is a possibility that only the actuator is defective and not allowing the valve to open. Try switching that actuator with a valve that is working properly. If the problem follows the actuator... then there is the problem.

regarding pump/motor temperature... that may be just fine. If you have a wet rotor pump the system water is used to lubricate the pump (there will be no place to add oil to the bearings) so if your water temperature is above 54°C then you would have a pump that is hot to the touch and it would be operating normally. If the pump is operating and the water is not hot but the pump is very hot. then there is a problem. Sounds like your pump is fine.

Yours truly,
Mr.Ed

Nic

Again, We’re so grateful. My wife’s sat in the room for the first time in years. Can I ask, if the water gets back to the boiler at a higher temp would that mean the boiler wouldn’t use as much oil to heat the water? Does the boiler only kick in when the return water drops below a certain temp? I hope that makes sense. 

EdTheHeaterMan

Pretty much that is how it works. But I think of it in reverse. The boiler starts out cold and the burner heats up the water. The radiators take that heat and transfer it to the rooms. The water temperature drops about 10°C and returns to the boiler. If the boiler heats the water faster than the radiators use it. There is a high limit that will turn off the burner. That might be about 82° The 82° water will then circulate to the radiators and return at about 72° eventually the water temperature in the system will drop enough to enable the burner to fire again. This is how old-school oil boilers work.

There are some newer oil burners that have 2 stage heat and variable heat input but they are not very popular in the States. Too many controls are problematic. Variable input is more popular on Natural Gas and LP Gas boilers.

I am glad you have a new comfortable room to enjoy.

Yours truly,
Mr.Ed

Nic

We’re very grateful and hope you’re all well. Thank you 

PC7060

Nic said:

We’re very grateful and hope you’re all well. Thank you 

No problem! Glad your rad is working and the boss is warm! 

JUGHNE

Let us know if you remove all the heads and things change. Thanks

Nic

I’m sorry, a questions just popped in my head. If I turn the TRV’s down on radiators in unused rooms will that mean the water returns to the boiler quicker and makes it use less oil? Sorry that just popped in my head 

PC7060

TRV = Thermostatic Radiator Valve.  Essentially it closes when the bi-metallic spring forces the seal down on the valve seat and stopping water flow. 

So yes, you can turn the valves up and down based on temp you want for room. 

If a bunch of the rads are shut down or have problematic TRV closing off water flow it causes the pump to work harder because it can’t push the water through the system (dead head). 

If the boiler is set to run based on thermostat call for heat but the pump can’t circulate water effectively because of bad or closed TRV, the system becomes very ineffective/ inefficient. 

EdTheHeaterMan

Nic said:

I’m sorry, a questions just popped in my head. If I turn the TRV’s down on radiators in unused rooms will that mean the water returns to the boiler quicker and makes it use less oil? Sorry that just popped in my head 

That is the basic idea. Just don't turn them completely off. You don't want pipes to freeze.

Jamie Hall

Nic said:

I’m sorry, a questions just popped in my head. If I turn the TRV’s down on radiators in unused rooms will that mean the water returns to the boiler quicker and makes it use less oil? Sorry that just popped in my head 

Questions have a way of doing that... yes, it will. And you will use less oil, since you are heating less space -- but not as much less as you might think, as the now cooler rooms will take heat from the warmer rooms. It's a bit of a balancing act. Be sure, too, to keep the cooler rooms at least warm enough that you don't have condensation problems.

EdTheHeaterMan

And what @Jamie Hall said

Nic

Perfect !! We’ve put up with this problem for years, hopefully you’ve all helped sort it. Excellent. 

JUGHNE

Possibly over the years someone has cranked down on the TRVs, trying to conserve energy, to where most of them were nearly closed.
If you pull off all of the heads you may have a different house as far as heating goes.

Happy wife...happy life!

Are you in the UK?

Nic

Sorry for the late reply. You’re 100% right !!! Yes we’re in UK just outside North Wales. To be honest the heatings never been brilliant or efficient, not sure whether it’s the boiler or the size of the radiators or both. It’s better now thank you but I’d love to correct it so it actually heats the house, just don’t know where to start. We’ve had plumbers out a few times who take a lot of cash but never really sort anything out 

JDHW

Have any of the plumbers commented on, or adjusted the balance of the system? The general idea is that each radiator is sized based on the heat loss for the room it is in - bigger rooms have bigger radiators. Then you have to adjust (balance) the system so that each radiator gets enough hot water to operate. Each radiator has two valves on it, a simple on/off or thermostatic valve, and at the other end of the radiator a lockshield valve that is used to adjust the flow through the radiator.

If you open up all the thermostatic valves then turn the room thermostat(s) up really high and let the system run for about an hour. Go round all the radiators and feel the temperature at the two pipes. One should be hot and the other one cooler. Do the cooler ends of all the radiators feel about the same temperature? If some are quite hot and some much cooler you have a balance problem. It is not difficult to sort out but you will need some sort of thermometer and some patience!

Best Wishes John

Nic

John thanks. In short no not one has done that, the one that wasn’t working is the biggest radiator but in the smallest room, which from what you’ve mentioned doesn’t make sense? They’ve changed the expansion tank, changed some seals on the boiler, did something to the rad that wasn’t working which obviously did nothing, he suggested it was a problem with the pipe work to that rad, which it obviously wasn’t. Lots of things. I’ll try that thank you, is it hard to do? If it means getting it running right I’ve got all the patience in the world 

JDHW

Nic
Does your system have a room thermostat(s) around the house - wall mounted little box that has a dial or a screen and buttons to adjust the temperature? Common location is downstairs in the hallway.

Try removing all the thermostatic radiator valve heads as you did for the non-working radiator and make sure the pins move freely as Ed suggested and I think you have done on the non-working radiator.

Then follow my suggestion about turning the room thermostat up high and feel the pipes. To see if the balance is roughly right just feeling the pipes will be enough.

I you want to be a bit more accurate you could buy an infrared thermometer (in the uk Screwfix https://www.screwfix.com/p/stanley-stht0-77365-infrared-non-contact-digital-thermometer/8374j) should work. Get some black electricians insulating tape and put a couple of turn around the pipes just below the valves at each end of the radiators. If you put the end of the thermometer about 2cms away from the taped sections of pipe you will get a quick reading of the temperature.

My comments on radiator sizes was a bit general. If you have a two floor house the upstairs radiators can be a bit smaller because you are gaining heat from downstairs and normally have bedrooms cooler than living rooms. A living room might have a bigger radiator because you normally want that room a bit warmer. As many people in this forum say - you need to do a heat loss calculation to size boilers and radiators properly and there are online tools for doing this. But to start with just getting you system working as it should is the first step.

Can you provide photos of the valves at each end of your radiators - they should all be similar so just a few photos will do.

BW John

Nic

Thanks John. Please see attached. Yes we’ve got the thermostat, I’ll pop to Screwfix today, that’ll come in handy. Nobody’s ever balanced the radiators so that might help. 

JDHW

Nic,
Before we go further - I am not a heating pro but I do have an engineering background and have installed by own heating system and designed/installed them for relatives (except the boilers). Happy to talk you through the balancing process if you are ok with trying on my advice.

You may have to wait a day or so to get the thermometer - it is not available for collection where I live.

Your first photo is a normal on/off valve and this will is probably in the area where your room thermostat is - this is as it should be because that radiator and the thermostat are controlling the general amount of heat the boiler is putting into the house. You should not have a thermostatic radiator valve on radiators in the same rooms as the wall thermostat.

Your second, third and fifth photos are thermostatic radiator valves.

Your fourth and sixth photos are the lockshield valves that are used to balance the system. I think your photos are from downstairs radiators because the valves also have drains on them to drain down the system.

I see that you have plastic pipes so the best way to measure the temperatures is to wrap the tape around the smaller nuts on the valves as they connect to the pipes. Wrap the tape quite tightly stretching it a bit to make good contact.

Once you get the thermometer make a list of two temperatures on each radiator using the process I suggested earlier. The hot ends of the radiators should all be about the same temperature across the house. The temperature difference between the hot and cold pipes on each radiator is the key number that tells you about balance.

BW John

Nic

Thanks John, your advice has been invaluable so I’m happy to take it. What should I do once I’ve got the temps? I’m sorry I’m my naivety what do you mean when you say this “ Once you get the thermometer make a list of two temperatures on each radiator using the process I suggested earlier. The hot ends of the radiators should all be about the same temperature across the house. The temperature difference between the hot and cold pipes on each radiator is the key number that tells you about balance.” 
Also, should the valves move more than a couple of mm’s? I assumed that they should go all the way down to close them, these only move slightly? Thanks, when I get the thermometer I’ll let you know