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Heating woes

(16 Posts)
EarSlaps Tue 16-Feb-16 21:00:36

I'm trying to figure out our heating system and it has me totally stumped! Our house just doesn't get warm enough and there are a few issues. House is 1960s, cavity wall insulation, double glazed, loft insulation etc. The upstairs stays pretty warm but it's the downstairs that has a problem. Downstairs is all open plan so a bit of a bugger to heat but the heating system doesn't seem to be helping. It's our first winter in here.

I'm an avid follower groupie of pigletjohn, so I'll list what we've got and what I've tried. This may be an essay but better to have as much info as possible!

Boiler is a Vaillant EcoTech Combi fitted in 2004, plumber who serviced it on moving in (British Gas- was a freebie service) said it was big enough for the property, and he repressurised the pressure release valve with a bicycle pump as the boiler was leaking. Pressure has been pretty stable since then, no leaks on PRV. I periodically bleed rads and repressurise but there is not too much air (normally just one rad but which one seems to change hmm). The air does have a chemical smell when it comes out and the water is clear. Can't see any leaks but a lot of the pipework is under wooden floors. No damp in the house and no problems with humidity levels so I'm guessing no big leaks anywhere.

The BG engineer noted the boiler was a bit sludged up so we had a magnaclean fitted in October by a local plumber (recommended locally and by a friend). I cleaned this today and it had only picked up a little dirt. When fitting it, he said it looked as though the boiler had not been properly serviced and parts that should have been replaced had not been done (can't remember what he said- seals? He said he would put a sticker on the boiler to show it had been done, and should be done at 5 year service). He said it could already be a bit damaged from dirt build up and might not work much longer- do I take this with a pinch of salt? We also couldn't locate the drain valve for the system anywhere, but I might have found it at the back of a cupboard in the playroom (ex garage).

TRVs are fitted on most rads apart from the bathroom ones. I unscrewed them, gently oiled and loosened the pins (they were moving but a bit stiff), then screwed them back on. They are Optima TRVs. All rads seem to have been fitted in 2004 too as they are certainly not 1960s radiators. Whole house was renovated at that point.

We had a Cosy smart thermostat fitted- this certainly switches the heating on and off at the right time but the boiler sometimes seems to stop working when the thermostat is showing the house is not up to temp. This evening the boiler was off and showing water temp of 50c, despite the thermostat being set for 22c and only showing 18c. The max water temp for the heating is set as 75c on the boiler. So the boiler is cutting out before it should.

The big radiator in the living room never seems to get properly warm- it is mainly cool at the bottom and I noticed that the pipe leading to the rad, the other side from the TRV, is lukewarm when that pipe is hot on other rads. So I'm wondering if it doesn't heat properly rather than cool due to sludge?

Yesterday the boiler was doing some major banging- it sounded like someone was hitting it with a hammer it was so loud! I turned the heating temp down from Max and that seemed to help and bleeding the rads seems to have helped a bit as I've turned it up again. Though there wasn't that much air.

Anyway, based on my essay (and if you haven't fallen asleep) what should I do? Do I need to replace TRVs? Just the heads or the whole valves? Do I need a powerflush? Is there a major problem with the boiler or will a few bitsbeing replaced help it? Or is there no point flogging a dead horse and I should just get a new one? I know we need to get a plumber in at one point, but hopefully if I sound like I know what I'm talking about I'll be less likely to get ripped off!

PigletJohn Wed 17-Feb-16 12:38:42

Do all the radiators get "too hot to hold" on the top, and "too hot to hold for long" on the bottom?

Assume that the nominal* heat output of a single radiator 600mm high and one metre long is 1kW, and of a double with fins is nominally 1600W, what do you calculate the nominal maximum heat output of the radiators is, and how big are the rooms?

Is the nominal output of all your radiators greater than the calculated heat loss of your house?

Do you know the power of your boiler? I understand you have a timer or programmer, a room thermostat, and TRVs except in the room where the room stat is.

*nominal is optimistically calculated under ideal conditions; actual wil be less.

The banging is probably due to scale and sludge deposits in your boiler. As well as the Magnaclean, you can add chemicals to loosen them. A DIY job is fairly easy and cheap, and worth trying first. A pro powerflush will cost some ££hundreds.

In an open-plan house, or any house if you leave the internal doors open, the warm air will rise upstairs leaving the downstairs cold. Is the downstairs carpeted, with concrete floors?

EarSlaps Wed 17-Feb-16 14:12:56

Thank you for the reply.

Only the upstairs radiators seem to get 'ouch' hot. The ones downstairs (excluding the towel rail in the downstairs loo) I can hold for a while and the big one in the lounge is noticeably cooler. Is it possibly a balancing issue then?

No idea on the power of the boiler but I'll look it up and do the calculations. It's a fairly big house and the living/dining/kitchen area is pretty big (from memory 4x8 m? for lounge diner). No doors between that and the hallway. Wouldn't have been my choice but putting in doors wouldn't really work as the house is now.

Luckily there are doors to the cold boiler/utility area and the playroom (with a ridiculously undersized rad in there- that's on the list to improve!). We just had the front door replaced with a Solidor as the old one let a lot of heat out and I've sealed around any gaps where I could feel heat escaping. It's wooden floors and I think they are layed over suspended floors as we have air bricks outside. There's a vent in the floor, I assume for the gas fire which was decommissioned by a previous owner, so I've popped a cushion over it as its under a shelving unit on feet. I've put a pillow up the chimney to stop draughts and we have thermally lined curtains.

We have a couple of rugs down but I'm thinking one in the hall and one by the patio doors could help as they are the coldest bits on the floor.

I've got a Gas Safe plumber coming soon so will see what he says. I have a not Gas Safe plumber friend who I could get to try and do a bit of a system clean before I try a £££ power flush. I'm reluctant to try one too early as there are always horror stories about the cost and any potential problems they cause, plus that they don't always work.

I think to be honest we could do with an additional heat source in the lounge to give it a snug feel. I'm not going to try using the gas fire already there as it looks like style over substance and all the heat would go up the chimney. I'm trying to persuade dh to get a wood burner for that romantic touch. We have a huge space we could use as a log store.

ArtyBat Wed 17-Feb-16 14:15:56

I have no technical advice to add to that of PJ above.

However, many years ago my parents bought an open plan, new build house, and it was always cold downstairs, as like PJ says, warm air rises.
The warmest spot was on the landing where I used to sit and read my books!

no useful advice whatsoever emoticon

ArtyBat Wed 17-Feb-16 14:17:08

err, don't know how that link came about confused

EarSlaps Wed 17-Feb-16 14:23:28

grin love that it links to a search for porn- what have you been googling?

I think a fire downstairs would help a lot but dh seems to think money would be better spent on a fancy holiday then wingeing about the cold the rest of the time [sigh].

It's alright most of the time just never gets cosy. The study upstairs is about 5c warmer than the rest of the house at any time. That's our cosy room.

ArtyBat Wed 17-Feb-16 14:42:30


When I tried it I just got a blank page with a notice saying the page had expired.......'tis true! Honest! grin

PigletJohn Wed 17-Feb-16 15:36:34

if you have a plumber friend, get him to put in some Sentinel X400. It is a mild cleaner that will loosen sludge. He will probably know how to inject it through the Magnaclean lid using the tube. Clean out the Magnaclean weekly as it will catch a lot, once loosened.


Just run the system as normal for 4 weeks, then drain it out through the drain cock and rinse it. Use X100 and X200 on final fill, and leave them in. You can add X900 if it continues to bang, and leave it in. Carry on emptying the Magnaclean weekly until it stays clean.

This will not be as effective as a powerflush, but it is much cheaper and may well do the trick. The cleaning is only water work so no gas qualification is needed. On an older vented system (tanks in loft) it is an easy DIY job as injection is not needed.

PigletJohn Wed 17-Feb-16 15:39:51


if upstairs rads are hot and downstairs are warm, it is probably a balancing problem (might be a weak pump or an open bypass). Start by turning off the hot ones. Do the others now get hot? Turn the TRVs down in the warmer rooms. They may have failed open.

If any of the rads are cold in the middle, they have sludge blockage inside. Cleaning may help.

EarSlaps Wed 17-Feb-16 19:50:07

Well, plumber today said it's pretty much not worth repairing. Estimates that it could do with about £800 of repairs (one part alone is £300) so is going to give us a quote for a new boiler.

I didn't tell him the previous plumber had suggested that we get a new boiler too, so two independent opinions from well regarded local plumbers means I guess we need to raid the piggy bank! He has suggested Worcester Bosch.

On the plus side he said the fitting shouldn't be too tricky as all the pipe work is accessible, we already have a magnaclean etc. He also suggested we change the TRV on the cool radiator at the same time as the others are moving up and down ok but that one is a bit stiff. At some point we'll probably try and replace the others as Optima are not the best but I might be able to get my dad onto that grin.

Spanglecrab Thu 18-Feb-16 17:27:07

I doubt you need a new boiler. When the boiler is holding off at 50 degrees if you press the button marked i what code does it give you? S7 would be my bet. Let me know.

EarSlaps Fri 19-Feb-16 07:59:54

It does say S7! So pump overrun dr Google tells me. Add that into seals needing replacing and a new casing (the inside has completely eroded) and it would be an expensive repair job.

Luckily a check of the finances tells me we could afford a new one then at least we can keep on top of yearly servicing. I've drawn up a new budget with it in and everything grin.

Spanglecrab Fri 19-Feb-16 08:26:58

G10 seal? Yep the inside will be damaged and all components would have suffered from excess heat.

Which boiler are you going for?

EarSlaps Fri 19-Feb-16 09:33:59

Yes, something like that!

The previous owners hadn't bothered to get the boiler serviced at all in the two years they were here. Before that it was rented out for a bit before being sold (maybe to wait until property prices recovered after the crash?) so I suspect it had the bare minimum of servicing done to meet landlord requirements.

The plumber recommended the Worcester Bosch Greenstar 42cdi. We have a large four bed detached with a main bathroom and en suite so that should be able to provide water for two showers at once. He checked the incoming gas pipe was adequate and our water pressure is good. I did ask him about a megaflow type system but he said it would be a lot of extra expense (fitting and servicing) and hassle for not much extra benefit in our circumstances. But might be worth it if we ever extended and added an extra bathroom.

Spanglecrab Fri 19-Feb-16 10:01:58

Sounds sensible.

The reason for the s7 status code worries me a bit. The boiler constantly measures the temperature of the water leaving the boiler (flow) and the water coming back in (return). The boiler will then modulate the flame to maintain the preset temperature differential.

The boiler goes to s7 or pump overrun when even on minimum gas rate the temperature differential between flow and return becomes too great. The boiler runs the pump with no flame trying to dissipate the excess heat before the boiler fires up again.

In the majority of cases the reasons for this fault can be found inside the appliance. Examples include a pump weakened by age, connection tubes becoming blocked (a common fault on older ecotecs) plus damaged heat exchangers and diverter valves.

On rarer occasions the fault can lie within the pipework in the wider heating sysyem. Pipes blocked by sludge etc.

I would recommend the heating system is cleaned prior to or at the time of installation.

In fact I'm sure that worcester demand it as a condition of warranty.

EarSlaps Fri 19-Feb-16 10:34:40

Yes, he would run a power flush first as required for the warranty (he's a accredited fitter of worcester bosch and has his own special pump thing for power flushing) and add an inhibitor etc. We have a magna clean now so that should help prevent problems in future- a different plumber said he'd never fit a new boiler without one.

Hopefully as all the radiators are modern, and a lot of the pipework seems to be too, there shouldn't have been too much chance for loads of sludge to build up.

It's so frustrating that people have these expensive boilers fitted then skimp on the extras like a filter and proper servicing. It's just one of the costs of home ownership.

Glad to hear he's not spinning us a line and it all sounds like good advice! It just seems silly to spend a lot fixing a 12 year old boiler that clearly hasn't been looked after in the past. My parent's oil boiler is 35 years old and counting! My dad does the maintenance on that most of the time and doesn't want to replace it for one that will only last 15 years as long as there are parts available.

Thank you all for your help flowers.

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